Confuzed1

iTrader: (4)

Anyone around running one of these blocks?

I read a little bit on them, and they seem to be a whole lot better than my stock 400 block that's currently .040 over which is a 4.155" bore on a 400. Supposedly, these Dart blocks can take a max bore of 4.185"...which is a whole lot better than a stock GM block.

I've been considering getting one with 400 main size....and before anyone says "why not get 350 mains" - it's because I intend to put all the internals out of my current engine into the SHP block, and I don't want to but another crank.

The one I have is a Scat 4340 forged. If I get this block, I'd have it bored to my current spec of 4.155 so I can reuse my SRP forged pistons instead of buying new ones.

There's nothing really "wrong" with the block I have, but I know there's no longer any room to overbore any further. If I decide later to go with more boost....I'm afraid it's going to get dicey relying on this block to hold up and be reliable.

A bud of mine also runs a 400 in his Camaro, and he has a almost new set of aluminum Edelbrock 70cc chamber heads with 195cc intake runners he's looking to sell....I don't know if they're the RPM's or what specific model, but he needs to come down in price a bit before I'd consider it.

I currently have Dart Iron Eagle heads on mine with 200cc intake runners and 70cc chambers....for a small blower application like mine, am I still better off with the aluminum heads even though the intake runners are a bit smaller?

In either case, even if I hold off on getting the Dart block for now...aluminum heads are almost a definite....any suggestions on heads?

FRMULA88

Your Dart Iron eagle heads are way better than Edelbrocks.

if you want to switch to aluminum heads, stick with the best quality
heads you can afford:

Dart
Brodix
AFR

Edelbrocks are better than stock, but can't compete with the ones mentioned above. They are nice "street heads" based on 40+ year old Chevy Design that's about it..

The entry level SHP Dart small Block is vastly superior to the OEM... so why not try the Dart SHP Alum heads?

http://www.dartheads.com/products/cy...aluminum-heads


I have the Little M Block & love it, I also have 400 mains for same reason. I started with a OEM 400 block and have
money spent on a forged 400 main crank that was in perfect shape when I changed blocks..

Orr89RocZ

iTrader: (20)

Aluminum would be better for heat dissipation and thus detonation resistance. Should beable to get more hp out of a more aggressive tune and allow more boost.

I would not get to aggressive on bore size with boost. Keep cylinder walls as thick as possible.

Nice thing about shp block is it has L98 style oem roller cam components. Makes it cheap and easy to go hyd roller. Ls7 lifters and find the spider/dogbones from an L98 or late model roller and have a great cam profile that will out power and out last flat tappets. Also more street friendly than solid rollers

Confuzed1

iTrader: (4)

Thanks for the replies guys!

Gives me more to ponder from now till winter...lol

The Dart Little M block also looks great. I also considered the Iron Eagle block, but I'd rather not get into raised camshaft location on the Iron Eagle....I would assume that would also involve a different timing chain, shorter pushrods etc. I understand the purpose to allow more clearance for stroker cranks, but I don't consider my Scat 3.75" crank to be a huge stroker crank....only needs a little off the oil pan rail for the rear counterweight and two other small grinds in my stock block.

I do already have a retro-roller hydraulic cam in mine now, so it will go into the next block also.

I guess the whole idea of getting another block is so I don't need to be concerned with bore size and thinner walls like I have now. I want to get a block that'll allow ample clearance for the crank, better cooling than a stock 400 block with priority oiling...just in case. And allow a 4.155 bore and have a little left over if I want more boost, or I need to over bore .030...and all my present components will fit right in to (except for bearings and rings of course)

Just like you're saying Orr, I'm looking. Into the aluminum heads for heat ,dissipation so I can get a little more timing advance and crank the boost up a few more pounds.

Kinda surprised about the Edelbrock heads. If you read some of the magazine articles , they act like they're the cats meow.....I'll look closer at others.

I'm willing to spend up to 18 to 2K for a good flowing, street able set that will play well with my setup.

Thx again!

Orr89RocZ

iTrader: (20)

2k will get you alot of head. Dart 200's with alittle clean up would be nice. Afr 195-210's are solid heads. Profiler has a great 195-210 casting. Pick your poison

DeltaElite121

Darin Morgan designed the 195's, but had nothing to do with the 210's (just for reference). The 195's can be ported out a good chunk to feed all the way up to a 434 no problem. That's the casting I'd get, personally. Buy them bare, send them off for porting and assembly.

Atilla the Fun

What's the HP goal? With a blower you need to care more about exhaust port flow. And that still means looking at AFR. As for the limits of production 400 blocks, I participated in one bored and stroked to a 441, that made 900 HP with an overdriven 8-71 on top of Brodix heads. It lived, street and racetrack, thanks to ARP studs, and a short fill of the water jackets. It was a 2-bolt block converted to splayed 4-bolt mains.

FRMULA88

The little M or SHP block can both be notched for crank shaft / rod clearance.

So can the Iron Eagle block, but the Iron Eagle block has some unique features / options:

raised deck option
raised camshaft centerline options
dual starter mounting points (standard)
big block camshaft bearings (standard)


http://www.dartheads.com/products/en...ll-blocks.html


For practical purposed the Iron Eagle has features I don't need so I went with the Little M.

Any of these 3 block are way better than the OEM Gen 1 SBC for a
hi-performance build.

ez2cdave

Very true ... LOL !

FRMULA88

How long did it live, and how much use? Even a short fill with block cement would limit usage on the street. Eventually block cement fails because it expands / contracts at different rate than cast iron.

Mine stock 400 made 656 HP, 13:1 compression.. splayed mains and ARP hardware.

The heads studs leaked water at start up on the dyno... (no blind tapped holes on a stock block) had to ghetto repair that with bars leak..

Then tore it down after 1 season due to piston damage caused by E85.(detonation due to insufficient octane)

further inspection also revealed polished areas on the cylinder walls that correlated with the head studs... (cylinder wall distortion)


The decision was made at that point to go with a new Little M block to eliminate all the issues that come with a stock block in a hi-perf. application.

Confuzed1

iTrader: (4)

I'm not looking at anywhere near that kind of power...
I use my car as a weekend warrior/street machine type of car. I'll admit, it's kind of a misfit with it being lowered with a few suspension goodies for handling, yet it has a 9" Moser and Nitto DR's that flex too much for real handling...

I have a small blower on it, a Magnacharger MP-122 with the semi helix rotors and bypass with no intercooler, so I'm looking to run low boost - around 5-6 pounds. I want to keep it low because its a cooler charge, easier to tune and more streetable (IMO). I learned long ago there's ALWAYS someone faster...

Shortly after I put the blower on, I had it on a dyno with a too-small 650 carb and smallish TES headers and the pulley the blower came with - only had 2.5 to 3 pounds of boost...still had the CAT on it too..and it managed 389 RWHP and 495 TQ. What makes it fun, is I was making over 400 TQ from 2800 to 4500 RPM's.

With the added few pounds of boost, a 800 cam carb, and the 1-3/4 primary headers I just put on it (CAT now removed). - I'd be happy with 450 or so at the wheels. So I'm trying to not be too radical - on purpose.

Ive always heard AFR heads flow real well, and people I've met that run them seem to like them. I'm running 9.1:1 compression with a NX276 cam...good with nitrous or a small blower supposedly. Pistons are SRP -21cc dished. What would be a good head to get? I'm looking at 70 to 72 cc chambers to keep the compression down.

Orr89RocZ

iTrader: (20)

Keep it 9:1 with aluminum. It will love boost and drive great

Confuzed1

iTrader: (4)

That's what I'm hoping...it runs great now, but I ended up going back down to the 3 pound pulley.

I recently tried my smaller 8 pound pulley (the smallest), jetted the 650 carb up a few sizes and set my timing for 36 total with vacuum adv. disconnected.

I then re-connected the vac advance and set my boost retard to take out 1 degree of timing per pound of boost...and it wasn't running right. Seemed like it was detonating anytime I got on it. Setting the retard up for 2 per pound didn't seem to help. Ran fine at part throttle.

This engine is VERY timing sensitive. If I retard the timing just a little too much, it'll run hot...too much and it pings. I'm hoping aluminum heads will help with the timing and allow me to run slightly higher boost without being so sensitive....

I'm looking at aftermarket blocks for better cooling, less cylinder distortion and hopefully more reliability.

watajob

iTrader: (29)

My next build, (HSR or Miniram 400), will involve an SHP block as the cost/benefit looks great. I just wonder why they stayed with a 2 Pc. RMS.

Confuzed1

iTrader: (4)

I agree - the cost for the block itself isn't too bad really. I wondered why they stayed with the 2 piece seal myself. Not that they're bad or anything, they were used for years...but the one piece is just a better design. A 400 HSR sounds like it'll be a beast!

If I did everything all over again, I'd go the LSX route no doubt. But I'm too far into all the parts for the Gen 1 SBC and would take a huge loss selling them off just to turn around and buy all the LS specific things required to drop one of those in.

It took me a while to save up enough scratch to contemplate doing a block and head swap. I'm looking at the AFR's on the common sites (Jeg's, Summit) and they're pretty pricey suckers!! -And they don't have any with 70-72cc chambers...only 65 or 75cc's. I don't want to bump the compression down any. The Dart Pro-1's seem a bit more down-to-earth on pricing, and they carry 72cc chambered heads with 195 or 220 cc intake runners.

You guys think I would be better off getting the bare castings and reusing all my springs, rockers, valves etc?? The springs I'm most concerned about since they match the cam I'm running. Lot to think about....

Oh - and BTW...when they say the heads are for a 350 OR a 400 SBC, does that mean the steam holes are already drilled in them, or do I still need to get that done?

DeltaElite121

I'll never buy assembled cylinder heads. Bare castings with my hardware of choice so I know FOR SURE there won't be any failures from someone else's lack of attention to critical details and/or subpar parts.

Confuzed1

iTrader: (4)

I decided to revive this post again. Winter's here and I'm once again looking at heads and wondering if it's going to be a real upgrade or not….I mean, why pay over 1500 bucks for a set of heads and see no real gain in power over the Dart Iron Eagles I have on it now?? I have decided to hold off on upgrading to a Dart block…for now. But I'm still looking at heads…if I'll see any gains from them.

Having a blower on the car is making it even more difficult for me to decide since depending on who you ask and what article you read tells you different things….

A few things I've read sound reasonable:

-Bigger intake port volume is not "better" on a street driven car. I don't want to lose velocity of the intake charge at the rpm's required for street driving..i.e. 1000-6000 rpm's.

My current Dart iron heads are 200cc intake runners, 72cc combustion chambers, 2.02" intake valves and 1.60" exhaust valves. Compression is 9.1:1 with -21cc SRP dished pistons. It's a 5.7" rodded 400 with a 3.75" throw crank.

My current cam is a Comp NX-276HR, 224/235 duration at .050" 113 LSA. Lift is right around .510/.520 using 1.5 roller tipped rockers.

Question #1- What do you think the min/max intake runner should be for good all-around performance…on a small roots blown 400sbc (6psi boost)?

Question #2- Are CNC heads worth the MUCH additional cost for a street driven car?

Question #3- How about intake valve size? Most have 2.02" intake valves, but others have 2.08"…

Question #4- Should I bother looking at heads at all? Spending up to 3K to gain 25 HP wouldn't be worth it to me. I know this is a subjective question, but what kind of gain -if any- from switching to aluminum heads?

Here's a few heads I'm looking at (among others)...


AFR has 215cc intake, 75cc chambered heads…they also have the 2.08" intake valves and are a bit pricey. They also have 195cc intake runner heads that look nice too. Using the bigger 75cc chambers might not be a bad thing on a blown car like mine…I've not figured it out, but I'd guess it would drop my compression to slightly below 9.0:1...

Dart has some nice looking heads too in their Pro-1 line of heads…they go from 180cc to 230cc with 72cc chambers. Few hundred cheaper than AFR's

Orr89RocZ

iTrader: (20)

After having 195 afr's and 245 speiers, two different builds on same 400" motor, i would say 195-200 cc that flow well are what you want on a street build. Much more brutal response in boost since you are keepin rpm range below 6000. If going higher and more power 220-230cc. I feel my 245's are slightly large. Work well but its pulling to 7100 rpm and not really nosing over much so thats alot of rpm.

A set of afr 195-210's, cnc or hand ported profiler 195-210's or even dart pro1 200's will destroy a box stock iron eagle head

Confuzed1

iTrader: (4)

Thanks for the response Orr.

I have a slightly better set of shorty headers on it now (1-3/4" Dons vs TES) , removed the CAT finally, and running a bigger carb (750DP vs 650DP).....always trying to find the best timing curve, etc...so I'm just trying to optimize as much power as I can with this blower. It's no slouch as is, but I know there's more...

So I take it I'm on the right track thinking 200cc intake ports then. Thing is, the Darts I have on it now are 200cc heads....just iron. Aside from a set of Pro 1's or AFR's being aluminum, is it simply getting CNC ports going to make that big of a difference? If you had to guess, how big of a HP gain over the Eagles I have on it now?

When you say the heads you mentioned would "destroy" a set of Iron Eagles, what about them is better for performance? I'm not doubting you...just asking.

And you're right...I don't need to go over 6K RPM's...the blower is done before then a power drops off...but then again, if the new heads will help it breath that much better, that could change?

Orr89RocZ

iTrader: (20)

Better port shape in same 200cc will have 20-30 more cfm than those irons out the box. With boost that can be upwards of 50-70 hp. Aluminum is also cooler running so it will give you more detonation control insurance.

I honestly dont feel you can go wrong with a set of AFR 195-210's or the pro1 dart 200's. just match springs to cam and get your compression where you want it. Could go 9.5-10:1 just about on just 6-8 psi. I'm at 17 psi at 9:1 and 93 oct gas only. Good intercooler and big cam helps

Rosewar

Hello Atilla the Fun
I have been reading a thread from 04-18-2010, 06:35 PM about what cam to use.I would like to ask You a few questions about what cam to use for My car,if You are willing to help I'll give you all the details later. Yes this my first post!!!
Thanking you for Your time in advance Justin

Confuzed1

iTrader: (4)

17 pounds on 9:1 compression!?! Wow...but that might be easier to get away within a centif or turbo blown engine. I'd think getting that kind of boost prior to 5500 RPM's, would make it tricky to run on pump gas...but I never tried it.

Besides, the roots blower I have makes 8 pounds max with the smallest pulley available...mind you that's non-intercooled boost at that. I'm running the next bigger up that puts it at 6 to 6.5 pounds of boost. I tried it at 8 pounds for a while, but tuning and timing get more tricky and sensitive. The iron heads might be contributing to those issues...

I was looking at the AFR's and Pro-1s, and I would most likely reuse my double springs for the retro roller cam I have in it now.

Confuzed1

iTrader: (4)

Might try to "Private Message" Atilla....most likely the easiest way to get to him.

Rosewar

Hello Confuzed1 Yeah I would do that but He has P.M. disabled,so I have P.M. two moderators to see if there is any way to contact Him....
Regards Justin

Orr89RocZ

iTrader: (20)

Correction, 24.5 psi now and over 1000hp on pump gas only. 9:1 comp. my motor is alittle loose for boost

Keep intercooled and you can likely get away with higher comp. i'm starting to think a street car only 8-10 psi max can get to 10:1 with aluminum and half decent sized cam

Rosewar

Hello confused1
I see that He has his p.m. disabled and I have p.m. two moderators to see if there is any way to contact him
Regards Justin

Confuzed1

iTrader: (4)

Well, I guess all I need is a bigger blower and intercooler and I should be up to 1100-ish HP in no time!

......NOT!

With that kind of boost/power, it's gotta be scary fast for sure. I'll stick with my lowly sub-600 HP slug...haha

In order to run that kind of boost, with that compression....on pump gas no less ....takes just the right combo of parts and tuning skills waaaay above my current skill level or expense account!!

Damon

Heads are always where the power is, even on a blower motor. Roots-blown combos are less sensitive to intake runner size than N/A combos, but there's no reason to go crazy. The boost basically does it's thing packing it in just before the intake closes, in my experience (at least at modest boost levels). Which is why you are still making good power even at very modest boost. It's NOT a turbo and it's NOT a centrifugal blower. It's its own animal. And it's got something nothing else does- a "one way valve" into the engine. There is NO back-flow.

There's a lot of good choices out there for heads, but whatever you choose you really need to figure out why that thing won't take more than 2-3 PSI of boost. You're missing half the fun. Get it up around 6-7 PSI and you'll be hitting your power goal easily even with your current heads. With some better flowing aluminum heads, no problem at all.

Heck, I'm making nearly 400 at the rear wheels @ 5 PSI with a RADICALLY INFERIOR Weiand 142 blower, a QJet carb, 8:1 compression and a Summit house brand flat tappet hyd. cam so small it almost passes for stock. I'm also down about 20ci vs. your engine (383). I've got some older-vintage AFR heads on mine, which I credit ast the primary reason the combo works as well as it does. Same same with stock heads would be down 40HP easy at the same boost level.

With a roots blower remember that the PULLEY RATIO determines your power output (if you can keep the engine in one piece). It's a POSITIVE DISPLECEMENT PUMP, not a compressor. How much boost your observe is a BY-PRODUCT of the restriction the engine represents to the blower's airflow. Nothing more. Same pulleys on a better breathing engine will show less boost but make the same power. Pulley it up to the same boost level on a better flowing engine and it will make more power.

IF you can tune it and not scatter the engine in the process.

Everything I've learned from my little roots-blown engine has been in the area of tuning. They're not all that different from other types of combos, but there ARE differences. Start with the basics- keep the compression lower than you think you need, don't get greedy with timing and keep it running on the safe side of rich.

cuisinartvette

X2 more than the OP would think. They are totally worth the coin. Get them and dont look back. Learned my lesson yrs ago about cheaping out over a few hun on heads. It cost me thousands to make them right, they are on my car now lol.

The Dart little M block is awesome imo worth it also.
Did a road race 408 awhile back for a member of another forum I was impressed. Thats one stout block!

Confuzed1

iTrader: (4)

Hey Damon!

The one and only time I had it on the dyno, it put out a max of 389hp and 495tq....that was with the 2 pound pulley, 650 Demon carb and TES shorty headers. I still had the catalytic convertor on it too. For what I had, I felt it did pretty well I guess....

Forward to the present....

I now have Dyno Dons shorty headers, ditched the CAT, threw on a 800cfm carb and put on a 6 pound blower pulley....I really didn't feel any big increase in power. And no, I didn't throw it back on the dyno....

So- I'm thinking there's a bottleneck somewhere....something holding it back, not allowing it to breath to its full potential. I really have nowhere to turn except for the heads....or cam possibly.

As I said earlier in the post, I had a 8 pound pulley on it briefly, but trying to set any decent advance curve/rate proved to be difficult and it was real finicky to tune. So I went back to the 6 pound pulley, and I'm happy with it overall...I just know there's more power to be had.....I'm hoping better heads than these Iron Eagles might be the ticket....maybe not.

Confuzed1

iTrader: (4)

As far as tuning in general, I have the carb set a bit rich, total mechanical advance at 36 degrees all in by 2200 RPM's. No real signs that it's detonating. But I do set my boost retard to take out 2 degrees per pound of boost. If I try to zero the retard, I do hear detonation.

Damon

I assume you let it boost about 2-3# before you start taking out 2* per?

That's the usual formula and it generally works reasonably well. I actually start around 1.5* per when I'm running a boost retard. (On my mild combo I run 28* total with no boost retard but I also run a significant amount of vacuum advance on top of that so it's plenty snappy off-boost)

Confuzed1

iTrader: (4)

No option for taking out 2degrees after it gets to any certain amount of boost that I know of...I could decrease it to 1 degree per pound of boost....or back off on total timing to 30 degrees or so.

I've tried all kinds of timing curves, total advance settings etc...all in by 2200 is about as aggressive as I can go.

Damon

Oh, you're using the old analog "boost adjust" dial mounted on your dash, then, I guess?

I hate those things. They're as twitchy as a 6 year old on a gallon of coffee. The number stenciled on the dial bezel does NOT correspond to what they actually give you in terms of boost retard. Sometimes more, sometimes less. I finally resorted to a test system that runs on compressed air to confirm the amount of retard supplied relative to boost pressures for any given dial setting. In general they do nothing, nothing, nothing... and then kick in the boost retard full and fast in a very limited range on the dial setting.

You wanna know why I don't run one now? That's one of the reasons why.

Set the dial to zero (or remove it completely) and do things the old fashioned way. It's just WAY more reliable and repeatable. On a mild engine with a small cam and an efficent little blower, you don't need it.

Boost is largely dependent on throttle position and little else. Mine smacks 5 the instant the pedal goes down and really doesn't go above 5.5 anywhere in the RPM range. What do I need boost retard for? I can just set the total where it works best at that boost and be done with it.

I then add generous vacuum advance on top of that for good part throttle performance.

My ignition curve is as follows:

8* initial
28* total "all in" by 2800
18* vacuum advance on top of that (which yields a true total max timing of 46* under appropriate part throttle conditions, similar to a stock low compression emissions-era motor)

I'll note that I have tried running the vacuum advance line to either the carb (full vacuum port) or to a manifold fitting below the blower (vacuum and boost). It works in either location, but I finally settled on running it to the manifold below the blower. I was concerned that a stock vacuum advance canister would not be able to survive seeing boost applied to it (blowing out the diaphragm), but with a couple years experience under my belt now I can tell you they are PLENTY tough to survive 6-8 PSI for extended periods of time. Of course, the vac advance won't retard the timing under boost conditions, it just goes to zero and stays there. But that is, of course, exactly what I want it to do since I already have the intial + centrifugal dialed in for best WOT scoot.

Just one of the little tuning secrets I've had to figure out on my own since I've never found this type of information anywhere. Big X-71 blowers and lumpy cams that are rarely driven on the street? Sure, plenty of info (lock out the timing, get a high stall converter and hit the track). But on the mini-blower combos with mild cams, good street manners and plenty of idle/part throttle vacuum?... nobody writes about tuning this stuff, especially not for dual-duty on the street and strip.

Confuzed1

iTrader: (4)

Yes, I have mine set up similar - guess I'm learning a little by all the experimenting I've done. I have a 12* bushing installed in the distributor which allows me to bump my initial at idle to 21-22 degrees. Then I'm adding 10 additional using manifold vacuum to the can for a full...32* or so advance idling.

I know that's almost a ludicrous amount of advance at idle for a N/A car, but with this blower it seems to run smoother and cleaner that way.

I suppose I could back off on the mechanical down to about where you're at, adjust my vacuum can to allow more advance and set total at idle to about 24 degrees with the vacuum can on full manifold vacuum....that's about as low as I can go with the advance at idle though. Any lower and it'll run richer and hotter. I would also need to change out the 12* bushing in the distributor to a 20* or so to allow more mechanical to say, 32 degrees at least (with can disconnected)....and then get stiffer springs in it to extend the curve so it's all in by say...2500??

I don't know...seems I've tried multiple combinations with timing, ported/full vacuum advance etc with mixed results. I can kinda tell when Ive gone too far with the advance, because when I go into full boost I can hear it chatter...that's where the boost retard comes in handy. I can twist the **** for a little more retard and it goes away.

IROCZ1989

iTrader: (1)

I went the shp route and its a great foundation for most street strip build. Here is a link to my build:

https://www.thirdgen.org/forums/engi...cs-within.html

On heads the you cant really put to big a head on a 400 +cube motor. That said Ive usually run afr on all my builds so excuse my lack of knowledge of the two mentioned heads here. I run 235 afrs with shaft system and if your looking to spend under two you can get almost any afr offering with titanium setup for under that. But the prices are going up this jan so of its in the cards good to act now. The bigger afrs flow very well on the exhaust port but the carry on up way past the cam you are running. IF you are really serious on the heads lmk I can direct you to the best price and where to get them. Take care

Damon

My experience is that once you HEAR detonation, it's too late. You want to run on the safe side of conservative especially at WOT. On my little 142 combo I've found that HEAT is the enemy. What is "safe" in the bottom gears is often too much in the long, slow pull across the stripe in top gear. Now, my 142 is well known for "beating up and heating up the air". Your much more efficient blower should be less prone to that type of behavior, but probably not totally immune. Every time I've had detonation it was in top gear, not revving quickly through the lower cogs.

And make sure you're not drawing enough vacuum at the carb to pull in ANY vacuum advance (if you have the line connected at the carb). Some of those cans can start pulling it in at only 2-3" of vacuum, which you can get close to in the upper RPMs, since you're drawing a LOT of air through the carb (plus any air cleaner restriction). I added a T fitting and actually watched the vacuum under the carb at WOT. It pulls about 1.5-2" vacuum at the top of the RPM range through an 800 CFM QJet.

Confuzed1

iTrader: (4)

Once you hear detonation it's too late!?! That might be just a little extreme don't you think?

I will agree however, if you're using the factory cast slugs, you'd better keep a real close eye on it. I'm using forged pistons which have been OK so far with mild detonation events that are very short term and corrected. I have bit more experience than most when it comes to detonation and what that does....I have shown you the pic I have of one of my JE hyper pistons and a snapped in half Eagle SIR rod.... right??

Thing is, I didn't even do that...the body shop blew my car up starting it on a cold day...lean backfire...BOOM...and it was over... Just got real lucky the block and crank survived....#1 rod and piston...not so much...

...I hear it when I'm pulling in higher gears also... like 4th or 5th at WOT and I back out quickly, apply more retard and I'm OK. Then I back off the total when I get back to the garage so I don't need to depend on the box to keep me from pinging. I like having the box on just in case I get a tank of crappy gas...which it's all crappy here with 10% ethanol. At least they say it's 92 octane.

When I began trying to tune this engine, I tried both the ported and timed port on the carb. But now I tee off from the manifold referenced hose for my power valve - basically true manifold vacuum under the blower, so I get what you say about vacuum being a little flaky on the carb when it has a blower underneath.

One of the main reasons my vacuum can only pulls ten additional degrees of timing is because I have the adjustment screw on the vacuum can turned in pretty far on the conservative side to make sure I don't ping at light cruise.

Anyways, I think I'll need to go back and re-tune everything once I put this 750 Demon in it, and different heads. I'll most likely change the springs in my distributor while I have it out so it's a little less aggressive. I'm running a Mallory Unilite...what a pain in the *** to change springs in that thing!!

I was thinking of AFR 210's, and I just read an article in which a 383 with a small blower (Weiand 177 actually) made over 550 hp and nearly that much torque using those heads...but the cam used was just a little more aggressive than mine.

Orr89RocZ

iTrader: (20)

You should beable to make 550 hp on a 383 with AFR 210's all motor Blower I'd expect 600-650

Tune up is key

Confuzed1

iTrader: (4)

I think conservative, but if I get more...I can deal with that!

EDIT: But I'm guessing I won't make 1018 HP like some people around here....

But I am curious....can you actually get I that kind of power to the ground in the 1/4 mile? Or do you need I to feather the throttle and try and keep it straight?

Confuzed1

iTrader: (4)

By the way, if anyone knows where I can get the best price on a set of AFR 1050's....post up! I'll order them tomorrow if I find the right price....I've seem "blems" being sold cheaper, but I'll pass on those...

I want brand new only...I don't want to deal with resurfacing warped heads, stripped holes etc.

Damon

No, actually, I don't. There's a reason I'm now running compression down in the toilet and modest timing. It was tough to learn, but I gave away NOTHING in terms of power and gained basically just "detonation resistance" in the process. Once you hear it, you've already been giving away power and hurting parts for quite some time.

My orginal combo ran 9.2 compression with iron heads. Then aluminum heads at 8.7:1. And now aluminum heads at 8:1 with the smallest cam I've run in any of the combos. I still make 2 more HP than I did with either of the other itterations of the motor. And no broken parts for 5 years!

Roots blower engines just don't work or tune like anything else. I used to run nitrous combos all the time so I figured a roots blower would be similar. It was not. It was an unforgiving, brutal task-master that slowly beat me into submission over a period of years.

Everything you're saying tells me you're on the same learning curve I was.

Confuzed1

iTrader: (4)

Damon, you know I've always listened to your suggestions on how to set up these small roots blown engines since I know you've been there....

Agreed, I would ultimately prefer not to experience any pinging at all...and any amount at all certainly isn't helping the engine. Maybe it's just me, but I need to experiment a little to find out what my max advance is, and I need to also experiment with how fast I can bring the advance in without any ill effects. I wish I were good enough to just listen to an engine and tell how's it's running, but I guess I don't have the gift.

Even though this blower is a little more efficient than say, the Weiand 142/144's out there, it's still non intercooled boost...and I have iron heads which doesn't help. My goal - like yours is to figure out a safe tune once and for all and not mess with it any more. I recently got rid of my 190 degree thermostat and opted for a 180 degree one. I also installed a nice set of dual cooling fans with a shroud.

Before I installed the fans, I was having issues of slowly overheating when idling or in traffic for long periods. Once I reached 240 degrees on a 90 degree day...i then realized the engine also starts to smoke when it gets to around 210 or hotter. Then I thought of how many times I've tried tuning this thing in the garage when it got up to around 210/220 and was smoking slightly.....now that I keep it cooler, it runs better, and I can actually tune it better.

Probably part of the learning curve you refer to. I've found that 400 sbc's need to run a bit cooler than 350's.

Anyway, this blower does differ from the Weiand in that it's intended to run on a sbc 350 with 9.5:1 compression. When I built this engine, I figured I'd go a bit more conservative with 9.1:1 compression. The cam I'm running isn't really radical at all....it's designed just for low boost or nitrous.

If I go with these AFR 75cc chambered heads, I'm guessing roughly I'll be at around 8.7:1. Once I get the heads and bigger carb installed, I'll tune it conservatively and see if there's any difference in power. I also have a MSD box with boost retard built in (that you don't like) to take place of my current one that doesn't have the multi spark up to 3K RPM's. Hoping it'll run a little cleaner at least since I jet it a little on the rich side.

Procharged GTA

Hi Confuzed,
I would definatley go with the AFR heads...as they have proven their self time after time, plus I like the 3/4" thick decks,which makes them really rugged in boosted applications. I would stick to the AFR 195 port even on a 400 to retain incredible low speed port velocity and throttle response, it will make so much power it will be ridiculous for a street car, you wouldnt tell no difference in a bigger port head, besides the loss of throttle response, a step on the smaller side is always a plus when street driving is involved. If I were you, I would also take a look at the MSD 6530 Programmable 6AL-2 ignition box. It makes setting up a timing curve very simplistic, you can start the boost retard at any boost level you want, typically, it could probably run on full timing until 2.5-3 lbs of boost, which in turn makes it much more responsive at the hit. We run it on dads truck with the 383, Brodix IK 180 aluminum heads, NX276HR, and the MP122 magnuson, works flawless. IMO 8.7-1 compression would be perfect for a premium pump gas blown street engine with 6-8 lbs boost with somewhere in the area of 30*-31* of timing "under boost"...... good luck with whatever route you choose, I will be following along...

Gotta love the little Magnusons, impressive little blowers!!!

Brian

Confuzed1

iTrader: (4)

Awesome info Procharged! I never knew about the 6AL-2!! Looks like a great system to me! I'll research it. I need to be sure it works with this Unilite I'm running...if this thing works as advertised, I should be able to crank the boost back up to 8 pounds!! Thanks!!

Also, I'll seriously consider the 195's again....guess I'm thinking this 400ish would be fine with the 210's as far as low rpm velocity...

Orr89RocZ

iTrader: (20)

195-210
Aint much difference between the two. You wont notice a difference

Procharged GTA

If you compare the "low lift" (.200"-.400" lift) flow numbers between the 195 and 210, the 195 flows about the same as the 210, the same also holds true on the exhaust side. What that means is the 195 will have better velocity, because its flowing the same, but doing it with a smaller port, equates to enhanced low speed operation.The 210 starts flowing better above .500" lift, but only by 17cfm at .500". If you were running a camshaft with up around .600" lift, or a strip only application, I would probably choose the 210. For a street car, always compare low lift head flow. If both heads flow almost identical in the .200"-.400" range, choose the head that flows it with the smaller port size, it will make for a more responsive street head..... you can have a big port head that flows 300+cfm up at .600" lift and above,which in turn; sounds awesome, but if it looses alot of low lift flow do to the bigger port, it will not make a great street head.....

Brian

DeltaElite121

I'll make a phonecall and see what I can do for you. There's really not a lot of room on the heads, honestly. You'de think there would be, but there's really not.

Confuzed1

iTrader: (4)

Brian - I was looking at the 210's for the exhaust flow also. The 200cc Darts I have on it now doesn't seem to hurt low end performance a bit. I didn't think 210's were a big enough change from those to effect anything. Honestly, I didn't think on a blown engine like ours, intake velocity would come into play as much since the charge is being forced in anyway??

But if your dad's engine responds well to the 180cc heads on a 383….maybe I should look closer at the 195's now….especially since me and your dad have a similar engine setup….wonder how that happened?

I filled out a head recommendation form and sent it in with all my engine specs to AFR just to see what they say.

Again, I also really like the sound of the MSD 6AL-2 your dad is running….being able to use full timing on the first few pounds of boost before retarding the timing should allow me to really dial this timing in!!

I'll admit…I didn't know what Damon was talking about in the earlier post when he mentioned pulling timing out after going into boost because I flat-out didn't know the 6AL-2 existed….

Damon

Even a blind squirrel finds a nut every now and then.

I've been getting more into boosted applications the last few years. Nothing fancy- 500-800HP range. Not 4-digit power levels or anything that exotic. But there are certain tuning similarities between the various applications that seem to apply in most cases.... like holding off on the boost retard until some nominal level of boost is observed.

Remember when you're off-boost you're really just running an over-cammed under-compressed N/A motor, effectively. Give it enough timing to keep some "snap" in it under those conditions, then dial back as the boost starts to build significant cylinder pressure where you don't want or need as much advance to belt out the power while keeping the hard parts safe from damage.