After breaking 3 pistons on my 305, I'm looking to build a reliable 350 to re-install the turbo on. The new engine will have a compression ratio of 8.5:1. I'm going to run 8-15psi of boost, intercooled. My goal is 450-600rwhp.

So far I've compiled a list of the engine components that I think will accompolish my goals. I'm planning to have an engine shop assemble and balance everything and then I'll re-install the turbo components myself.



I'll be using the Holley Commander 950.

Any suggestions for the engine?

 

Good luck I'm doing the same thing but I think I am going to get more power than I think... 350hp base +6psi from what I've seen on ***** burners 6psi will yield you 40% more hp with the right turbo...

 

glad to see you're getting back into the game; considering you were using a stock LG4 long block on your last setup and the power it made I don't hardly see how you won't make 450 outa this one. (to the wheels that is)
This is what I'd do to the bottom end, in order of importantce. IMHO spend a bit extra for H-beam rods, I-beams would work but I suspect it won't be worth taking chances with honestly. If you go to the trouble of line honing studs in the mains instead of bolts would be fine. The cast steel crank is definitely better then a regular cast OEM crank, but if you can find one used go with a GM 1053 forged crank should be about the same cost. With some prep these are great cranks.
Ditch the summit heads for iron eagles, worlds, or vortecs. Double humps and similar heads are fine for someone wanting an old school street rod, you want to make power. any of those will do it way easier not to meniton have a better combustion chamber not to mention you'll be in for only slightly more green.
With ~8:1 CR, those forged pistons and the H-beam rods I think 8 PSI would be "light duty" on a motor like that.

 

For an 8:1 engine only running at 8 psi, you'd probably be ahead running non-intercooled, and putting the intercooler $ towards the bottom end. Compare to the earlier Buick Grand Nationals... I'd either up the compression to 9:1 for 8 psi, or up the boost to 10-15 psi at 8:1. Saving for another month to get some aluminum heads would help keep detonation down (and probably free up another 50 hp, as well as dropping the intake temps), and let you run an extra .5-1 points of compression. A forged crank and some h-beam rods would add a ton more strength to the bottom end without much of a cost penalty. It's easy to say "well, it's just another hundred..." and end up at 2-3x your budget!

A.

 

I'd probably go with a better bottom end over better heads. IMO provided you don't run something crack prone I'd run nearly any 1.94/1.5 valved head that keeps the CR sane, even something like a set of L05 heads. Syclones came with 64CC heads (swirlies at that) and made 285hp and had what basicly amounts to the peanut cam. You'll have 33% more displacement compared to a 4.3L V6 as well as a cam that doesn't suck. The other reason I'm saying to just get a set of good used heads now and put $$ into the bottom end is that you can always come back and upgrade heads way easier then you can put new rods in the motor; the crank isn't essential but with the main studs that should take care of most anything you'd ever want to do on the street, and I like the notion of building for whatever may come along or running junk ***** to the wall.

The pistons you're using are also the most common replacement for Syclones and they run more then 8 PSI albeit intercooled. IMO if you're gonna only run 8 PSI just get a JY motor and use it; I have a feeling your goals will change after you get it in and running good though, especially with the EFI.
Even something like a powerstroke intercooler would be a huge difference. The hot air GNs (the EFI ones) made 200hp, the intercooled ones made 245 under rated hp.

 

Thanks for the comments. You guys are right in that I want the bottom end to be able to hold up to almost anything. Also, 8psi will probably only be a starting point and it will allow for a lot of improvement down the road. The connecting rods are something that I'm still unsure of. I can't decide if the h-beams are worth it for how much more they cost compared to i-beams. Also, I already have the intercooler too, so no money to be saved there.

Along with the engine, I'm planning to have my 700R4 re-built to the max to be able to handle the extra power. I also want to replace the stock torque converter. I have heard good things about vigilante converters, but they seem a little pricey. With the 305, boost started to build around 3,000rpm, so I'm guessing that the 350 will be able to spool it lower, maybe 2,500rpm. Does that sound about right? (t6 1.05a/r) Also, if that's close will I want a torque converter that has a stall close to the boost threshold?

Thanks for the help!

 

If your'e gonna do a 700R4 get 4L65E internals (the 5 pinion planetary, hardened input shaft etc.) so it'll hold up. Dependent on how far you want go, you may want to consider other options for a transmission both cheaper and more durable. A converter is an excellent idea it should get you into the power range of your turbo quicker. I'd call Vigilante and tell them your combo (be sure you know your H/C/I, static CR, car weight gearing the type/size of the turbo you're using etc.) so that they'll know what range of stall you need.
Dependent on your heads and cam, I could see power coming on even a bit lower then that. They'll have a pretty large effect on what you're dealing with.

 

Has anyone actually broke hard parts in a 700? I’ve shattered the governor assembly in one into a million pieces but none of the parts that are actually used to transfer the power.

OTOH, I have roasted frictions in them doing all sorts of stupid things, seems like they are the week points and let go well before hard parts do.

 

The bottom end I would change a bit. As someone else said, use a forged crank. Boost add a lot of cylinder pressure. Then, go with a quality set of H-beam forged rods, and a good set of forged pistons. With proper fueling you can safely run 9:1 at 10-12psi.

Go with a mild cam. One just a step up from stock. Turbo's don't like big cams. Even a stocker would be sufficient.

Heads... Unlike what some people have said DO NOT sacrifice here!! Turbo motors make power by being able to flow, so you want that to be good. The biggest mistake so many people make is dumping a bunch of money in the bottom end, and throwing on a crap set of heads, and wondering why their motor doesn't make near the power they thought it would. Get the Vortecs, they're cheap and flow well, even better if ported.

Oh, and under no circumstances should you run non-intercooled. Sure, it works fine on smoe older stock 4 and 6 cylinder cars, but they run small turbos and low boost levels. Oh, and it still caused problems.

 

We roasted the sprags in a friends '84 T/A on a nitroused 350. He also busted the input shaft on the same pass.

 

If you are using a used block, it's not much more to build a 383. That extra 33 ci will get you much better torque before the boost even kicks in.

If the block is new, don't worry about it, stick to the 350.

 

All the engine parts are going to be new, including the block. zixxerpilot, a forged crank wouldn't hurt, but I can't see a good cast one being the first thing to fail if something goes wrong. I do agree that a mild cam is the best for a turbo and so far I'm looking at the Comp Cam CCA-12-253-4. It's a little bigger than stock with a wide lsa.

I'm also looking at the Hughes 22-25L converter. It's a 12" with lockup and 2500 stall. Summit and Hughes both recommended that one for my setup.

 

hm, the one thing I was going to say was to use a bigger cam... That's so small... huh, I guess your preference...
wait, ok, your first post cam seemed small, the 12-253-4 I think would work great.

I second the thought of upgrading the rods. The first ones you mentioned where basically entry level I beams, stock replacements. Once you start upping the boost you'll wish you had better. Summit "stage 2", or eagle H beams would work great there.
Any reason why a 6.75" balancer over the 8" one? Make sure your timing cover is setup for that, boy that's a pita to realize at the last minute!
I wouldn't even waste a gasket on the torque intake. A performer RPM is $112 last I checked. Unless you plan to go to FI in the very very near future that is.
I would go with a normal oil pump (not high volume), with the mr gasket high pressure spring, and the steel driveshaft. budget $40 total for that.
I noticed the summit dual roller timing chain was $31.99, when the comp version was $32.99, chances are it's just a sticker change, but I went with the comp just in case, IMHO.
I'd also use a 2 piece timing chain cover. The summit stamped chromed one was $13 last time I checked, worth it's weight in gold for future cam swaps, or to fix leaks.
and of course, make sure your builder opens up your ring gaps, .020-.024" on the top 2 should be good.
Rock on!

 

I have a 2 piece timing cover and it is nice to change out some of the hard parts but you have a real hard time getting it to seal properly!

 

I'd run a fully forged bottom end...

 

I'm running the Cloyes 2 piece cast alum cover on my Dart LittleM, and have never had a problem with oil leaking there (they have a cover to adjust the advance angle). Many friends are running the 3 piece covers, and haven't had leakage either. Which one do you have?

My valve covers are a different story. I've got stamped steel, and dimpled, to clear the turbos on the Gale Banks manifolds (note - anyone planning on running these will have a much easier time with tangential exhaust housings, instead of on center!). They don't seal well at all, even with The Right Stuff and the rubber valve cover gaskets, so I'm taking my cast alum (that hit the turbos), and cutting out the interference and TIG welding in sheetmetal.

 

I agree w/brodyscamaro.. work on the bottom end.. you can always replace the heads later. I still dont know why you want to make 450 under boost when that is simple to do on a all-motor setup. Go for the big #'s!

 

If you were running a stock engine, I would suggest running 450hp, however, you are building an engine, let's see lower 600's.

 

Thanks for all the advice so far .. it's been helpful. The 2-piece timing cover is a good idea for future cam swaps. Is it best to go with a normal volume/high pressure oil pump?

As far as the target power, it's just a starting point. Once I get a good tune and all the issues worked out, I'll probably up the boost and the engine should be able to handle the extra power. I'm not so sure about the drivetrain though..

 

For the turbo system, stick with a stock pressure, but high volume pump. This will be sufficient for the engine and won't be to high of pressure for the turbos. If you push too much oil pressure, you will burn up the bearings since the oil will be moving to fast to acutally cool them. (Maximum Boost - Corby Bell) has a great write up on this.

 

I went to that section on oil lubrication and re-read it and you're right. I also posted a revised parts list to see if I could get any of the parts for a better price. Everything is from Summit except for the h-beam rods, which I found eBay sells them for $100 cheaper.

I talked with the machine shop that will do all the labor for the build. They don't install Comp cams into the engines they do, b/c they had too many problems with the cams going bad. They recommended Crane, so I switched to that.

I also changed from a 1-piece rear main seal block to a 2-piece. This puts the oil dipstick tube on the drivers side, which works out better. I changed the crank, flexplate, and oil pan to work with the new block. Is there anything else that needs switched? I saw for a 2-piece timing cover an 8" harmonic balancer can't be used, so I went back to the 6.75".

Thanks again.

 

why those rocker arms? Those are identical to stock ones. Are yours worn out?
I'd recommend the comp roller tip ones, something like CCA-1412-16 or CCA-1417-16 if you can stretch the budget.

That cam is more duration on exhaust than intake.. why did I think that turbo cams are backwards of that?

I'd just be extra careful with the 6.75" balancer and that cover. It says will not fit 8" balancers, but i'd just be very careful, such as making sure it points to 0* at TDC, during the build.

 

Askulte has some good advice. The nickel & dime parts will chew up money quickly.

Have you looked at the Crane 212*, 216*, 218* single pattern cams. Since you are carbed there is no real PROM/ECM idle tuning problem. They would have approx. 10* more overlap than the Crane 210/216 you chose (-15* overlap).

 

Yeah, the rocker arms are stock replacements. Those others are better, but cost too much.

Also, I've decided to sell the blowthrough carb setup and switch to the Holley Commander. In that case, am I better off using the cam with the 114 lsa?

 

I tend to like 110* LSA cams over 114* LSA cams. That is more of a person choice in terms of powerband preferences. The 114* has less overlap and therefore is easier to tune at idle. We are talking about small cams here so it doesn't really matter that much. You can probably tune just about anything with the Holley ECM. I have never tried one though.

The real problem is when the engine has more cam overlap and big injectors. Tuning VE at idle needs to be more precise due to the injectors. I am running a 110* LSA (-4* overlap) and 42#/hr saturated injectors. It took some tuning to get it to idle properly with a 730 ECM and $58 code. I run open loop right now full time.

I am not saying to go with one of the cams I mentioned. Take a look at them in terms of the powerband you are after. Comp Cams has some power curves at their website to show the characteristics of their cams. I kind of use that as a rough guide. David Vizard's cam & valve book has some good info in it too.

 

I decided that if I didn't use a forged crank, I'd risk the chance of regretting it later on. I found a Cat crank on eBay, and I'm curious if anyone had any experience with that brand.

I'm also changing type of transmission I'll be using. Since I'm buying another TA for the engine project anyways, I might as well find one that has a manual tranny, since I'd rather have that. With that in mind, will I want to re-think any of the decisions I have made with respect to cam choice or anything else?

 

The last time i broke this 700R4, the friction material was totally scraped off. One of the pins or something holding the sun gear came off and then it turned into a blender. Thats with just my 305 motor. I lost count of how many times i have had it rebuilt. The external tranny cooler helps a lot, and changing the fluid and using a shift kit. The tranny guy held up the friction plates and looked at me puzzled, some of them were only worn off on one side. The interesting thing is, those 2.73 gears are still kicking in the differential.
Someone chime in about the price, is that $4000 a little high for an engine buildup for just a 350? My friend had his 350 rebuilt into a 383 with forged pistons, crank, full roller setup for under $2500, and the engine builder told him that its ready for nitrous. I'm not trying to split hairs here, but does GM have a vortec crate engine he can drop in that has forged internals?

 

I wish I could find an engine that I could just drop in. The problem is that forged crate engines are built with high compression and to either swap the pistons or heads is going to drive the cost up.

The good news is that I already purchased the car that the engine will go in, and I plan to start acquiring the engine parts next month.

 

I bought my entire rotating assy, Little M block & heads from gofaststuff.com. My other camaro had the same stuff from them also.

 

Sounds like a very nice setup, but one ?. Why only 8 lbs of boost? You could run 20+ lbs with that setup, with a good tune. Say hello to like 650+ rwhp. Good Luck!

 

Just thought you should know, i am running non-forged G.M. powder metal I-beam rods. So i would say a good forged I-beam rod would be fine. But i might just be pushing my engine the limits.

As far as converters go, you get what you pay for. A good converter is going to cost you, but its worth it. I have an art carr 3500 lock up converter and it cost nearly $800. But i love it. I had a TCI 3500 lock up that cost like $300 and there is a big differance. The art carr converter feels so much bettewr and my times dropped alot from it.

 

Heh, I know.. 8psi will be a good starting point to work on the tune and get everything running right. After that, I'll start moving into the double digit boost numbers.

Also, the car I'll be using has a manual tranny, so I don't have to worry about picking out a torque converter. Thanks for the advice though.

 

So far I have purchased the rods and crank, and I'll have the heads very soon. I also am planning a trip to Summit to pick up the rest of the parts in about a week. I decided to go with aluminum heads and a different cam. This cam has more of the power range I want. Is the 112 lsa good enough?

 

Any cam will work... 112 might be good, depending on the specs of the rest of the cam. You'll want more intake duration than exhaust, due to the backpressure being 1-2x boost pressure, unless you get one of the top shelf $$$ new design turbos, and optimize the headers/downpipe perfectly. FWIW, I'm running 236/230 @ .050 Comp cams on a 113 LS, with my 399, AFR210 heads, and single plane intake. Idle is a bit more aggressive than I expected.

 

Thanks for the info. I guess I'm stuck between choosing 2 cams.

1) Crane 113522: 218º/230º, .459”/.486”, 112º lsa, 1800-5800 rpm

2) Crane 114201: 222º/222º, .450”/.450”, 114º lsa, 2000-6000 rpm

I want a good idle and powerband up to around 5500rpm. Turbo is a Garrett T6 and I'm estimating spool-up will start around 2500rpm. So far exhaust is 3" all the way back (no muffler/cat).

 

Why not get a custom ground cam? They aren't really much more expensive from Comp, or other companies, and you'll get something that's a better for your setup.

 

The problem is that I don't know what cam specs would be optimum for my setup. So, I'm kind of stuck picking out one that I think is 'good enough'. I guess in the end it's not too important since the turbo will be making the power anyways .. considering what a completely stock engine was able to do.

 

This is what I suggest. Bullet proof block and lots of great feedback on this engine builder. You get a forged assembly with a dart block for the price some places offer a stock block forged assembly. Check turbomustangs.com there is a guy in the 8's with a shortblock from them and I also picked one up but don't have it running yet. You tell them the compression you want.

http://dynoflow.substorm.com/short_b...eetpro_355.asp

Cammotion is the popular choice for custom turbo grinds

http://www.cammotion.com/

 

I know how you feel. I have played around with cam timing numbers in an Excel spreadsheet I made. I picked 218* @ .050 for the intake and 212* @ .050" for the exhaust. I move the open and close times around and compare to other cams posted on turbomustangs.com and Vizard's book. Sometimes I like the 112* LSA and sometimes it looks like the 117* LSA is better. I still can't make up my mind. Search for cam posts by 83 Crossfire TA. He has some good info about turbo cams in this forum.

Out of the two Crane Cams you posted, I would choose number 2 with the 222* duration and 114* LSA.

What kind of exhaust are you running from the heads to the turbo(s)? Length and diameter? What is the A/R on that T6 that you think will spool at 2500 RPM. It sounds like a small A/R so that means more exhaust backpressure and less cam/valve overlap.

EDIT: Is that a single 3" pipe with no muffler or cat? If so it will only flow for about (((3/2)^2)*3.14*110/2.2) = 350HP before building back pressure. Take that into account when choosing the cam.

 

Yeah, I ran into a couple of 83 Crossfire Ta's posts on cams and he really knows his stuff. From the heads to turbo, I modified Corvette manifolds and made a 2.5" crossover pipe. The a/r on the T6 is 1.05 and on the stock 305 it started spooling at 3000, so with a good 350, I'm expecting it to happen earlier. For now just a single 3" pipe from the turbine outlet. I already have it made up from the last setup, and it will be a pain going any bigger. Eventually, I might, though.

 

Just an update.. I made a trip to Summit over the weekend and picked up the rest of the parts. Now I have everything and just have to drop it all off at the engine shop.

I'm curious, once it's all together, what should my max rpm be (combo at the top)? I'm wondering b/c with the 3.70's, I'll be around 6k at 120mph. At the track, I should trap at least that, so I might be running above 6k. Just wondering if that will be a problem?

 

I've seen DynoFlo's ads on Racingjunk.com but was skeptical about ordering.. that 598 at the time (before I went TT w/a 406) is a excellent deal... I just had never heard of them. So you ordered a shortblock and recieved it already? were there any hassles w/the seller?

 

I would of like to have gone with the 406 but had the turbos in hand and the 406 would have been to big for the turbos. Great to deal with & quality parts. I've had to call back after I got the short block (took 2-3 weeks from time that I ordered) and they took the time to answer my questions. There are some guys on turbomustangs.com that also had good experiences in dealing with them. Haven't fired the engine yet but from my experience and research they are legit.

The only pain I had when I got the short bock is finding all the plugs and pins for the new block. LOL If I'm in the market for another I will buy from them again.