DIGGLER

iTrader: (1)

still putting my money on the heads/cam being the culprit.

Big Dog Chevy

Yeah with that big a cam and lower CR no wonder that car wasn't hitting the numbers. Do a DC check using 9.5-9.7 as the static CR and see what you get. Your low to mid torque was way down. You could have run a off the shelf cam with that package and did much better at the track. IMO

skinny z

If you get the chance, have the machine shop degree the cam. The finished deck height is also important. Those installed numbers can prove to be very useful. You'll need them to calculate your DCR. It may an idea to have those numbers before you order head gaskets. The gaskets may be your last opportunity to fine tune the SCR to be in line with the heads, cam and how it's installed (advanced/retarded).

mcbchild

iTrader: (1)

I think he said the block was decked .025 and says this should bring my compression up to nearly 10.25:1 with .041 head gaskets. So I am guessing I need thinner head gaskets. Hard to find thinner for alum. heads.

skinny z

.025 is pretty much the stock deck height.
Victor Reinz head gaskets are .026". Aluminum compatible.

EvilCartman

iTrader: (1)

If you're looking for some really thin head gaskets, .015 rubber coated steel shim gaskets. Been running them for a couple years now, no problem so far.

skinny z

4.06" x 3.75" 388ci
Cc vol. 63cc
Flat top piston 5cc
286/294 108LSA/105ICL
6" rods
.025" piston below deck
Fel Pro 1010 .039 x 4.160 10.7 SCR 8.3 DCR
Victor Reinz 5745 .026 x 4.10 11.1 SCR 8.6 DCR
Fel Pro Z1094 .015 x 4.10 11.4 SCR 8.86 DCR

skinny z

Do these gaskets need retorquing after a couple of heat cycles?

DIGGLER

iTrader: (1)

cutting the deck and thinner head gaskets will help some, but its not going to pick up 150h+ rwhp.
i dont remember now, but were these heads ported by someone?

Big Dog Chevy

[quote=DIGGLER;4245727]cutting the deck and thinner head gaskets will help some, but its not going to pick up 150h+ rwhp.


I really don't think that is going to fix your problem, it would help but not solve your lack of performance for your combo. You have the motor out now, this is the chance to get it right cause if you don't you won't be happy when you put it back in and don't run the numbers. Been there done that. IMO

DIGGLER

iTrader: (1)

what i would do right now if this was my car and i had the engine out.....

1. if the heads were ported by a local guy, i would assume he ruined them. sell them or get rid of them somehow. get another set of heads and DO NOT let anyone local touch them. unless you are local to t.e.a. or something like that.
most old school/local guys STILL believe you have to hog out a head to make it flow. they do not have a flowbench, and they just hog out heads according to what will work good IN THEIR MIND. which, 9 times out of 10 results in a hogged out head that makes less power than it would have if it was untouched. i know IHI on this board has firsthand experience with this one.

2. ditch that donkey **** cam and get something in the 240's duration. just a simple, nothing crazy off the shelf cam would be fine. custom would make more, but if the heads are junked up, i would take care of that first.


take care of these 2 issues and the car would lay down 400-450rwhp. which is roughly 100-150rwhp more than you made before. and, helpful side effects would be increased vacuum at idle and better all around driveability, and you can back off of your spring pressures. you wouldnt HAVE to have stud girdles or other big beefy valvetrain items. you could drive the car around on the street with no problems. oh and better fuel economy while doing so.

skinny z

Just to refresh things.
3400 lb race weight.
Best trap speed of 111 mph.
Best et of 12.5x.
Best 60' of 1.9x.
With those numbers that engine should be producing about 355 rwhp.
An ideally set up 1/4 mile car should be able to high 11's with a 111 mph trap speed.
With 355 rwhp, add about 20% and you get around 425 chp.
If that sounds right then there may not be 100hp to find.
Does anyone agree? ( Not too far off Digglers numbers depending on which end of the range you look at.)

Big Dog Chevy

That sounds right to me, thats why he should go to the dyno to make sure the power is there. I did a Camaro that goes:
355 chevy 2 bolt 350+whp at 6000rpm with 52mm tbi convr
3600lbs with driver, full power, steel hood and working heat/ac
3.42 with trutrac
full bolt ons
off the shelf Comp 212/218 @.050 HR cam on 110lsa Retarded 6* (that's the key)
16" dr
1.7 60'
107-110 trap mph
mid to low 12 sec et.
16+ inches of vac
I don't see why he needs all of that cam for that motor. It bleeds of too much cylinder pressure for me. He's was running the same numbers as that Camaro I did BUT he has a bigger motor, better heads, better induction, lighter race weight, better trans, gears and converter. I don't get it. I hate to see guys that are sooo close but yet sooo far from having a complete package dailed in. I see guys at the track all the time with big small blocks or big blocks with cams so big the car barely idles, they run full 29" slicks on gutted out cars with $2500+ heads and spools and the damn car barely run 11.90s. I love to race those guys. Better get it right mcbchild or you won't be happy when it comes time to run it.

DIGGLER

iTrader: (1)

i have a
350cid engine w/11:1 compression....
200cc ported factory LT1 castings
23x/24x hydro roller cam
vic. jr. intake

puts down 425rwhp through a th400, 9" rear, and 28" slicks. i figure his motor should at least make that much or 50 more.

skinny z

Even the most optimistic dyno simulation shows 450chp at 6000rpm.
Your higher compression and roller cam make up a lot of ground.

DIGGLER

iTrader: (1)

...so what does my engine make in the dyno simulation? my cam is basically just a comp cams 306 for an LT1. peaks around 6500 on the dyno.
just curious to see the difference between mine and his in the simulation.

EvilCartman

iTrader: (1)

I've never re-torqued them down. They've survived driving on the street and quite a few passes down the 1/4 mile, some with 200 hp worth of happy gas.

skinny z

I assumed a few things for the data needed in the simulation. Some info I gathered from previous postings.
350 cid.
LT1 heads (using stock flow data).
11:1 SCR.
750 cfm induction on a single plane intake.
Small tube headers with mufflers.
07-306-8 cam installed straight up w/1.5 rockers.
534 chp@6500.
452ft/lb@5500.
If you remove the small tube headers (which is about the worst simulation) and replace them large tube open headers the theoretical power jumps to 609@7500. That the demonstrate the huge advantage of a well tuned exhaust.
With that cam and SCR you have a DCR around 8.2:1.

skinny z

[QUOTE=Big Dog Chevy;4245980]
I don't see why he needs all of that cam for that motor.QUOTE]

Mostly because the Brodix don't come into their own until around .500".
My Vortecs and Digglers LT1's (porting notwithstanding) flow 227 and 213 cfm @ .400" respectively. The Brodix are 209cfm@.400".
If you go into the curve a little further, the Vortecs and LT1's are at 229 and 215 @ .600". The Brodix are 267cfm. You need a bottom of the page solid roller to wring the most out of those heads.

DIGGLER

iTrader: (1)

wow, not what i was expecting.... that sounds quite a bit high. it actually made around 440chp@6200 with the stock heads and large tube headers.
with the ported heads it makes around 510chp@6500.
my heads flow right at 247@.400 and 290@.700.

i believe the brodix track 1 heads mbchild is running have similar flow #'s albeit possibly larger ports than mine.

skinny z

I find that the simulations are predictable but optimistic. I'm a big believer in a properly spec'd exhaust and think that a lot of dyno numbers (both real and simulated) take advantage of headers and collectors that would have a hard time being adapted into a vehicle. Keep in mind too that dyno's live in a perfect world.
That being said, you have one hell of a set of ported LT1's!
I going to get into the dyno simulation again later and do a direct comparison between your set up and Mcbchilds. I want to make sure I didn't mess up on the data input. The simulator will also plot full flow figures based on the ported values you've provided so I'll mess around with that too.
By the way, what were the specs of the dyno headers? Primary tube diameter and collector size and length?

DIGGLER

iTrader: (1)

that would be cool!
i never had my engine on a dyno, i have only used chassis dynos so far. and, i was simply adding 20% to whatever the car dynoed. (no idea how close or far off the 20% number is on my car)
exhaust on the car is a set of hooker supercomps 1 3/4" primaries into dynomax bullet mufflers mounted on the collectors.
my intake is a vic. jr. with a 1200cfm throttlebody (converted to efi)

Big Dog Chevy

Mostly because the Brodix don't come into their own until around .500".
My Vortecs and Digglers LT1's (porting notwithstanding) flow 227 and 213 cfm @ .400" respectively. The Brodix are 209cfm@.400".
If you go into the curve a little further, the Vortecs and LT1's are at 229 and 215 @ .600". The Brodix are 267cfm. You need a bottom of the page solid roller to wring the most out of those heads.[/quote]

I understand, and needing a good roller cam is what I've been saying. You can't get the lift without duration on a flat tappet cam like you can with a roller tappet. But will that make a 100-150hp diff? You take that same 355 on that camaro and change out the small cam (which he's going to do) and it's going to gain 40 more horses. That will put it close to 400whp on a 2 barrel. I'm just comparing mcb's setup to other setups that are running the same or better numbers with less parts. The ported sportsman II heads flow 252 cfm @ .500 and 262 cfm @ .600. You brake down mcb's setup and everything say it should be doing low 11's right but it's not so that meens somethings not right. I just think mcbchild has a miss match setup and IF the motor and tunning was ok then the parts selection does not match and maybe that's why it's under performing. I was hoping that he found something in the taredown that would explain the big power loss but it might just be a lot of small things that's the culprit. IMO

skinny z

I haven't had a lot of time however after going over some of the data:

350 cid w/Brodix Track 1 heads/07-306-8 cam.11:1 SCR.
516chp@6500.
454lbs/ft@5000.

350 cid w/ported LT1 heads/07-306-8 cam. 11:1 SCR.
560chp@6500.
479lbs/ft@5500.

388 cid w/Brodix Track 1 heads/Isky cam. 10.12:1 SCR.
452@6000.
447lbs/ft@4500.

388 cid w/ported LT1 heads/Isky cam. 10.12:1 SCR.
483@6000.
461lbs/ft@4750.

mcbchild

iTrader: (1)

The heads I have were never ported and I only had the heads milled to 63cc from 65 cc to keep my compression up. I also think that my rings were bad and since the shop is re-honing the block and installing new file fit rings, I should have some of my power back that I lost. As far as how much, I would estimate 75 to 100 hp. I felt the power fall off after maybe putting about 400 to 500 miles on the motor and the power fell off so badly, that I couldn't even spin the back tires at half throttle anymore. The shop swore that nothing would be wrong internally. Since that time, I have had my old sportsman's II heads inspected for cracks, flat milled and also installed new springs and a new valve job. None of that help, that is when I ordered a new custom cam from isky with the new lifters and springs and that did not help. Removed the old 3500 stall converter and purchased and new one and still did not help. That is when I decided to buy new heads and got the Brodix track 1s and only had them milled down to 63cc and nothing else. Had the carb cleaned and rebuilt at another performance shop and the only thing they notices was a blown power valve. The car did pick up a little more power after the new heads, but still not near the power it had new with only a couple of hundred miles on the motor. The car did over heat once when my fan belt flew off and seems to me that was about the time I loss all that power from the motor around 400 to 500 mile on the motor and had never been the same since. The shop told me that he noticed the burn mark on the side of a piston, but did not damage the piston. I wonder if that could have destroyed the rings and not able to maintain tension on the rings.

Big Dog Chevy

See you spent all that time and money and none of the things you changed made a diff because they were not the problem from the get go. Once they finish the motor you should be on the right track. But I still say go roller! lol

mcbchild

iTrader: (1)

I will probably go with a roller setup over the winter, but for now I should be making pretty decent power once I get my motor back. The shop that built and has my motor now has an ideal roller setup for me and we are just going to go with the setup I have already and see how that does. Maybe once I go roller, I will up my stall converter to about 4500.

Big Dog Chevy

Sounds good, maybe when you get your car up and going I can bring my car up there and we can go at it. Just for some test and tune of coarse.

mcbchild

iTrader: (1)

Sounds good.

mcbchild

iTrader: (1)

Hey Skinny, Can you re-calculate my power level with the same specs, but with a true 11:1 compression.

DIGGLER

iTrader: (1)

it would be nice if the rings would fix it, but i dont think thats it either. it would seem that if your losing 75-100hp from the rings, there would be issues of severe blowby. it would probably dang near blow the valve cover breather/s through the hood. also, the compression test you did on the 1st page of the thread looked pretty decent.

since the heads are untouched, i would keep rolling with those and ditch that cam. or, if you REALLY want to keep running it, install it straight up.

skinny z

388 Brodix Track 1. Isky cam. 468@6000. 459@4500. 11:1 SCR.
That's around the 4% per point average.

mcbchild

iTrader: (1)

I still can't believe that my hp and tq is still that low with my setup. I guess maybe choosing a different cam needs to be done really soon. I just thought that with the heads I have 221cc, 2.08 int/1.60 exh. would really help this engine breath. I was informed these are better heads than my old sportmans II 200cc and now it sounds like I should have kept those heads.

Big Dog Chevy

Been trying to tell you. You do have some good heads but it's the entire package that makes the power not one thing. You have the cubes, heads, and induction just need to put it all together with a few more matched items. If you want to go faster then 12s that is.

DIGGLER

iTrader: (1)

have you thought about retro fitting some stock roller lifters in this block?

skinny z

If you put Digglers cam into the Brodix 388 things perk up a little more.
500 hp from 6000-6500rpm.
477 lbs/ft @ 5000rpm.
That's with 11:1.
The Brodix are excellent heads however they don't flow as well as the fully ported LT1's.
The simulation shows that those heads can use lots of cam. The SCR has to keep up though.
Getting your DCR closer to 8.5:1 with this hydraulic roller means a SCR of almost 11.5:1. That's a .015" gasket on a .025" deck block.
Power goes a bit to 510hp @ 6000-6500 and torque to 484 @ 5000.
So far that's 60hp with a cam swap and appropriate compression ratio adjustment.
If I use that engine in my car (see sig) in the Drag simulator you're going 11.5's at 117 mph.
If you bump up the stall speed to 4500 rpm, launch at 4000 and shift at 7000 you may see 11.10's at 120.
( Remember simulators live in a perfect world. This just lets us compare apples to apples)

mcbchild

iTrader: (1)

Sorry all for getting back on here so late. Well after some time of letting this car sit, I finally am going back to work on it. I had the blocked 0 decked, re-honed, new pistons rings, I am keeping the same cam for now and had them install the cam straight up and all the internal parts looked good from what the shop said and they just cleaned up the pistons. I did discover that after all the time of trying to find my lost power, it is the trans that is slipping really bad and that also explains why I couldn't get my mph up to where it should have been. I am having the trans rebuilt with more hi po clutches, HD Sprag and install the 4500 stall converter. A buddy of my that works at a trans shop in Bolingrook, IL opened the trans up and said that the clutches are shot and the front pump was bad on that trans. Once this all gets put back together, I should have better launches with the tranny finally doings its job and the 4500 stall converter. I hope to see 1.5x 60ft and some really low consistent 11.x and maybe get it dyno tuned to hit a couple 10.x

Big Dog Chevy

Now you are getting some where. That thing should leave real hard with a true 4500 stall.