Any suggestions or advice on my tenative engine build/ combo would be great

[Z28lt1rocket]

ok so of course this is a forum and Im not talking directly person to person to some engine builder but Im not a total newb but I expect to get some bs comments but what Im looking for are realistic honest good advice if thats possible.

what ive been looking into and figured out so far is:

-350 LT1 block 2 bolt main have it converted to a 4 bolt main splayed end cap

-looking into a Callies complete rotating assembly that already balanced

-3.25" stroke (327 ci crank) 4.030 bore (.030 over) with 6.00 inch rods = 331 cubic inches

- I will also have the block decked to achieve the desired compression ratio and plan on running a typical 64cc combustion chamber

- Or would a larger combustion chamber be better for a better quench area on a forced induction motor?

-aiming for a 8.00 : 1 compression ratio yes this is on the low end but if its boosted I rather have more room for more boost than a marginally high compression ratio.

-heads I plan on running are AFR 210's or equivalent if any better suggestions

-90mm single Turbo (not sure on the a/r spec need to call and talk to turbo techs lol if thats such a thing) I want peak power/ boost to occur at 6000rpms

- plan on running about 20 PSI of boost

- intake manifold will be a hurricane professional products single plane with the EFI 860 elbow and a twin 58mm LT1 throttle body

- plan on spinning the motor to 7000 RPMS

- Camshaft select too be determined ( not sure what a good turbo cam is, and could care less about lope, whatever makes the most average torque easy to tune and max horsepower for my combo is all i care about and let the specs follow)

- using the stock computer right now and will be buying a 3 bar map sensor to compensate for the lack of tuning on the stock pcm and will make a custom table that divides the stock parameters by 3.

- using tuner cats software

- what size radiator would be recommended as well ? and part number ?

-Fuel management is also to be determined. any help on the correct injector sizes need and what fuel pump is recommended as well and what fuel pressure to use would be great too (stock is 42 psi not sure if increase it would be better)?

thanks any input advice ideas or relevant pictures would be great. plus any Idea on the rough ballpark horsepower and torque this combo would make? like minimum to its maximum potential ?

[firebird_1995]

Not much bs here friend. We're like the home depot, you've got questions, we've got answers. But first, some more questions from me... what are your goals for the build? What is is going to be used for? (Street only, strip only, street/strip, or max effort build). Is budget a concern?

[Z28lt1rocket]

Believe it or not Im in New York and currently drive me car literally ALL year around even with fresh snow on the ground (dont dwell on this too much or get side track on how but I really do studded tires and 6 inch wide stock salad shooters). So tempatures and winter summer tunes are important. but back to what you were wondering I plan on daily driving it with taking it to the track occasionally so I want it to be streetable, gas mileage is no concern. Budget is mildly important but im not looking to be a cheap person and then end up with problems later (rather o it right the first time). Horsepower goals I am clueless on I just know what platform I want and let the platform dictate the amount of possible power. Slightly backwards but I know what will work together smoothly just not sure of the outcome if that makes sense.

[firebird_1995]

Makes sense. My feeling are this... forced induction is expensive. You can probably get into FI for as little as 3-5k but it won't last. For reliable forced induction setups you are looking at a minimum of 8-10k in engine alone. Supporting mods (a trans to handle the power, rear end that won't grenade at the track, sticky tires, suspension mods to make it all come together is going to bring you into the 15-25 range. So with that on the table, is that near what you are looking to spend?

[Z28lt1rocket]

yes I understand its insanely costly but this is going to be a project car with no time limit on it and will be using another car in the mean time. So im basically in the research phase of the motor build, Ive already looked into the necessary complimenting upgrades.

[blackbirdws6]

I would bump the compression ratio since the car will be a dog out of boost. Coupled with turbo lag, this build would be rather peaky in terms of power. I'm at around 9.3:1 on mine with roughly 19lbs of boost. The power profile will be different with my blower vs the turbo of course. Are you going with less stroke to simply spin this thing harder? I'd trade cubes for RPMs personally. Look into Shownomercy's turbo build. It has some unique details but isn't overly complicated. That car makes excellent power with more potential left in it.

[shownomercy]

90mm turbo, 8.0 SCR, and 330ci?

You will need nitrous to lite that turbine off sometime before peak RPM IMO.

You may want to evaluate things as far as goals for car and parts picked to get there.

[Fastbird]

I'm interested to see this done as stated above on one main point. The destroking. You're getting a really favorable stroke to bore ratio there, should make a very efficient setup. Downside is not a lot of CID, but that can be managed.

Critiques based on your original post:

If you're going to spin to 7, bring your power peak target up some. You can't expect to carry max HP another 1000 RPM, and torque will continue to drop off. By shifting your powerband higher, you'll be more efficient on the top. Your camshaft selection will be a big determining factor in this, so talk with your engine builder.

Don't go with the 6" rods. I never recommend those on FI builds because it has a dramatic impact on the compression height of the piston (the distance from the piston surface to the wrist pin, the longer rods push the pin higher and reduces the amount of material for your ring lands weakening the piston). A 6" rod is too much even a 355 IMO. go with a 5.7 for the above reason, weight, and it'll let the motor spin quicker and easier.

With that small CID, I wouldn't step up to a large frame T6 turbo. Will take FOREVER to spin up. I think actually the venerable Precision 76 GTS (7675) with it's .96 A/R would do awesome on that motor.

SCR of 8.0 is ENTIRELY too low. Myself and another guy are at 8.8:1 and that's about the lowest I'd go on one of these motors, as it seems to be right at the threshold of too low. I'd target more like 9.0-9.25, maybe a tad higher if you'll be using aftermarket EFI in the future.

Don't overcam the motor, especially with a turbo. Wide LSA, low overlap, low duration. You don't need a huge cam to make big power with a turbo.

Injector sizing is going to be dependent on what your power goals are. Quench, head selection, etc are best reserved for your engine builder. I'd definitely get the builders input on head port size for a smallish motor like that to ensure you maintain velocity and don't end up with port stall. Yes, you can run heads that are too big.

Stock fuel pressure if 43.5 PSI at 0 vacuum. This setting is usually fine. A good regulator will increase pressure on a 1:1 ratio with boost.

What are your power goals for the motor? Overall driveability with a broad curve or are you looking for a top end screamer?

Take what you're estimating on spending. Double it. Then add 50% more. That should get you close.

[Z28lt1rocket]

ok thank you everyone for the advice its VERY useful and seems to be matching up with what the other techs Im talking to are saying. I spoke to numerous people today.

BLACKBIRDWS6 Yes I am purposelly going with less stroke so it will spin higher rpms easier and faster.

on cam selection:
Lunati gave me a single pattern .526 lift 114 lsa and 224 dur at .05
Comp cams gave me .540 228 dur and .510 230 on a 116 lsa
Crower gave me a single pattern .520 lift 210 duration on a 115 lsa

I spoke to trubonetics and they said the recommended their "midframe series" with a 75/ 75 = a 1.00 A/r

I spoke to SCAT enterprises on the rotating Assembly and they recommended a 8.5 to 8.8 : 1 compression ratio for what im doing

Horsepower goal ultimately I decided roughly on 900HP since they told me I had to have a horsepower goal to figure out how much fuel and other components i need to match up with


...and FASTBIRD Ill look into the turbo you recommended Thanks !

[blackbirdws6]

Pretty small cams for a 900hp goal.

[Z28lt1rocket]

I thought so too.. but I don't have enough knowledge to know what sounds right and what doesn't. Naturally aspirated, I could tell exactly everything that would work well with anything. Turbo... no idea... all of them keep telling me that I dont need to go big for a turbo application... and they were more concerned about the boost PSI I planned on running than my horsepower goal.

... What would you suggest BLACKBIRDws6 ?

...especially since im going to be running AFR 210 heads on a 330ci motor... granted its forced induction but still they are pretty big for that size motor and flow up to .650 lift and theyre only telling me lifts around .530...

[shownomercy]

Any mid frame T4 unit will work fine.

PT7675, the TC7875, Comp 7675 are all popular small turbos. You can step up to a PT88 on a T4 if you can find one, or get the new PT8847.

Or, be brave, run a T6 flange and get a S475, S480 etc...

[blackbirdws6]

I thought so too.. but I don't have enough knowledge to know what sounds right and what doesn't. Naturally aspirated, I could tell exactly everything that would work well with anything. Turbo... no idea... all of them keep telling me that I dont need to go big for a turbo application... and they were more concerned about the boost PSI I planned on running than my horsepower goal.

... What would you suggest BLACKBIRDws6 ?

...especially since im going to be running AFR 210 heads on a 330ci motor... granted its forced induction but still they are pretty big for that size motor and flow up to .650 lift and theyre only telling me lifts around .530...

Cam choice will be determined by a number of factors. I'm not sure if you plan on putting together yourself but I would ask the guy who will be building your heads/intake setup what would be best. For my build, I spoke with Lloyd Elliot and he provided a lot of great info which helped me decide on a cam. I would assume a cam in the 226/230s range with lift nearing .590 on a 115lsa may be ideal. You will need a good valvetrain with solid seat pressure to avoid floating the valves at high rpm. Going with more duration can allow a bit more lift to help keep the valve stable.

[Z28lt1rocket]

ok thanks BLACKBIRDws6 and SHOWNOMERCY.

[Z28lt1rocket]

another thing is what should the ring end gap be or should I use gapless rings ? and whats the benefit and drawbacks?

[Fastbird]

Pretty small cams for a 900hp goal.

turbo cams vs blower cams are two different animals. Remember the owner of PTK, I do believe he went over 900 with a 76GTS on a 355 with a 218 single pattern cam. I've talked this over with Lloyd also and am currently stepping down from the 234/244 .610/.610 110* cam that was in my car to a 223 single pattern, .575 lift, 113* lsa cam and expect to pick up a lot under the curve, make more power, and carry power higher and farther than the old one because I'm not blowing boost out the exhaust.

[blackbirdws6]

another thing is what should the ring end gap be or should I use gapless rings ? and whats the benefit and drawbacks?

Best to check with the ring manufacturer. For reference, my top gapless ring is at .030 since I am around 19lbs of boost. I had a bad experience with my last gapless ring set but it was determined they weren't the problem but my cylinder bores were. Supposedly the gapless sets will provide a better seal than conventional but you will hear comments go back and forth. The guy who recently refreshed my engine recommended the gapless again so that's what I went with.


turbo cams vs blower cams are two different animals. Remember the owner of PTK, I do believe he went over 900 with a 76GTS on a 355 with a 218 single pattern cam. I've talked this over with Lloyd also and am currently stepping down from the 234/244 .610/.610 110* cam that was in my car to a 223 single pattern, .575 lift, 113* lsa cam and expect to pick up a lot under the curve, make more power, and carry power higher and farther than the old one because I'm not blowing boost out the exhaust.

I agree completely with your first statement. The rest as mentioned comes down to having someone with experience making a recommendation since this wouldn't be a typical build. There are so few working turbo lt1 builds for reference which make it a challenge to try and compare one build to another for part reference. 900hp is doable but still a lofty goal considering few have done it and usually it's with more cubes. I know a big cam isn't necessary here.

[shownomercy]

Fastbird, I run a LE 224/224, you will like it.

I run regular piston rings from JE, nothing fancy. So far, they seem to be working, I also went with their recommended gaps which was around .025 I think.

[MoeHorsePower]

Everyone is correct, Like said your compression is way too low even for the 331, it will be horrible on the street from a stoplight, Mine is at 9.4.1, custom cam with a 78mm Turbo, T4. on 10lbs it has made 703 HP so far, no meth, Just to give you an idea. Lag? everyone at the shootout saw what the lag did to my Dennys Nitrous Drive Shaft...

[popo8]

Everyone is correct, Like said your compression is way too low even for the 331, it will be horrible on the street from a stoplight, Mine is at 9.4.1, custom cam with a 78mm Turbo, T4. on 10lbs it has made 703 HP so far, no meth, Just to give you an idea. Lag? everyone at the shootout saw what the lag did to my Dennys Nitrous Drive Shaft...

lol.. ohhh yeah we did.

LTXtech.com is my DRUG!