Quinny

I am looking to put together a pretty serious engine for a 3rd Gen Camaro. The car will be street driven, but I want to be able to hold its own in dyno comps, drag racing, burnouts etc, so it needs to make plenty of power and be built tough.

I have spec'd out the following plan so far:

*Dart Little M 400ci block - 4.155" bore, 4 bolt billet splayed caps
*Callies Compstar 3.75" forged crank - total displacement 407ci
*Eagle/Scat 5.7" H Beam rods
*SRP -16cc dish forged pistons - approx 9.0:1 compression
*Solid roller cam (specs: 280deg advertised duration, 245deg duration @.050", .624" lift, 114 LSA)
*Dart Iron Eagle Platinum 230cc iron heads (300cfm @ .600 lift)
*Twin Garrett GT35R turbos, .82 rear housing
*Intercooled
*Fuel Injected
*Turbo 400 trans, racing-spec

According to a power calculation program I found, power comes out at approx 1220hp at 6500rpm on 25psi - and I spoke to an engine builder who said that the figure looks about right.

Now, it will be kind of a budget build, so I don't want to spend money where it isn't needed, but I don't want to cut corners and end up with a dodgy combination. It is a project car, so it doesn't really matter if it takes a little while to get it all together, but I want to make sure it is done right the first time.

Can anyone offer any advice about this combination - good, bad, otherwise?

One thing I am not sure about is the cam spec - it needs to be a solid roller cam, and the specs I have listed above work well on the dyno program, but going shorter advertised duration and duration at .050" made more power. However, I am not sure what a cam with 270deg adv duration, 240deg @ .050", .600 lift and 114 LSA would be like because I have never seen a grind like that.

Also, does anyone know whether the GT35s will flow enough for this combination or would I be better going to a GT40R or something similar?

Any advice would be appreciated.

Cheers,
Ben.

AutoRoc

I would also do a solid roller like you are thinking but a LOT of people make BIG power with a hyd. roller, especially if you are keeping the specs small and the rpms low. Don't guess on the cam, have it custom made by a professional turbo engine builder who understands your goals and combination of parts.

I would do a single turbo also probably a 80-88mm depending on what kind of power you want to make(1000-1300)... 1 of everything is much cheaper than 2 of everything. If you are dead set on twins, I'd do no smaller than 66mm twins.

This kind of power is useless on the street, if you weren't aware of that.. tirespin city..

I would do Oliver or Carillo billet rods, not Eagle/Scat H beams. Diamond pistons over SRPs...

Pro1 heads vs. Iron eagles... Do aluminum..nobody needs 50+lbs extra in their engine bay...the turbo setup is gonna weigh enough to begin with.

Goodluck and goodluck with your budget. $25,000 sounds about right for the powertrain.. goodluck keeping it under that number. Please post pics when you are finished, I'd love to see it.

Quinny

Thanks for that. I spoke to a cam grinder before and he said that a solid roller is the way to go, because it is a bit big for a hydraulic setup. He said that to make max power at 6500rpm it will be roughly 246deg @ .050", lift in the mid 600s, and around 114 - 116 lobe sep. The final specs will be determined when I have exact figures for intake manifold and head flow, turbo manifolds, compression, gear ratios etc.

I would prefer twins, and the GT35 is a 700hp turbo, so it should fit the bill nicely, I was a bit concerned that it wouldn't flow enough at the top end, looking at the figures, it gets very close to the choke line on the compressor map at 25psi and 7000rpm.

As for the power on the street - that is part of the reason I want to go EFI, so I can use a boost switch to run different tunes based on boost level. I will need to talk to a tuner and see what can be done, but I should be able to get an ECU that can be easily adjusted for 3 or 4 different boost levels.

Alloy heads are alot more expensive than cast, and the Eagle 230cc ones flow about 297cfm at .600 lift, and the PRO1s are around 306 from memory, so it isn't a massive difference, but you're right, the weight factor is something else to consider.

As for the budget, well, if it costs $25k, then it costs $25k, it might take me a little longer to get it all together. It is a project, so it isn't like it needs to be together right now - though it would be alot of fun!

The funny thing is that I could build it naturally aspirated making 600hp for about half the money... half the money for half the power....

SupplySgt.

yes yes yes defintely post pics when you get it all together i am really looking forward to see how this comes out. definitely has promise i'm jealous

AutoRoc

This will get very expensive if you're farming out ALL of your plans to professionals..20-30 grand for a combination and you want to save $300 with IRON heads over Alloy? come on now.

Last I checked Jegs sells the Iron Eagles for 1100+ and the Pro 1's for 1400+... $300 to save 50lbs alone is worthwhile when you're looking to be quick.. I probably wouldn't run those heads box stock either. Intake and head portwork will help you get more out of those turbos also. Don't forget that with twins it's double everything. Double the cost, double the parts, double the damage if there is engine trouble.

Over here a few of the big name turbo engine builders are Steve Petty @ ProLine, Mike Moran, Nelson Racing Engines, Kenny Duttweiler.. I'm sure you've done research but they may have ideas for you.

Quinny

You are right about the heads, it is probably worth going alloy.

I am planning on doing as much work as I can myself, so it isn't all going out to pros.

I am sure that the engine builders you mentioned are great... but it might be a long trip - I am in Australia.

AutoRoc

Yeah I noticed.. haha I have no clue how or where you get your parts from. I think Nelson would have the best ideas for you if you wanted to tickle their brains. They do a LOT of 1000-2000hp street engines, I wouldn't mind owning one myself. Ask them if they have a "mild" TT 400 cube engine with your goals in mind, what compression they run, what size turbos.. I don't see why they would keep basic info top secret and it's possible they can even direct you to parts purchases, shipping tips, etc.. Goodluck!

jay_rich

I just got my budget build running, but i had the motor to start with.
383 lt1, all forged and splayed 4 bolt mains, ported heads intake etc.

I build a custom kit with a T6 74mm garrett. After buying all the piping, rad, intercooler, turbo, injectors etc I was around 3000ish. Then my trans died so I put a TH400 in and a new 3600 stall converter. So thatw as another 1500.

I have a build on the forced induction section.

For ur build...twins I would say 2 67mm turbos OR just get 1 t6 flanged 88+mm turbo. Like a PT88, or a borg warner turbo.

Jay

RealQuick

Ben here is my advice:

Cam selection for turbos is funny... typically any cam will make the power you want... but cam choice will definitely affect the driveability and where you want to make peak power. I would lean toward the mid 240's as well for 6500 peak power. Any reason you chose that rpm (did you calculate your trap speed vs engine rpm)? If it you can do with less rpm, but keep the same power, then obviously that is the way to go. With high boost like you want to run, high spring pressures are needed, so solid roller sounds like the way to go IMO.

What are your dyno/track goals?

At your cubic inch, the GT35r's can probably support 1100rwhp... but will be out of steam before 25psi by my guess. If you want to push that much boost, so to standard twin T76 T4 turbos. Building boost at the line for a drag acr shouldn't be an issue.

If you need any help with the build of the kit, or questions, shoot me an email at jon@lt1boost.net

slomarao

I would consider different parts for the shortblock. With your goals i would go much higher quality.