Guys,

Im new here- First post as I need help with my build.

I'm building a 408 twin turbo with two GT3582 R 0.82AR turbos. CR will be 8.8:1.

Basic setup is:
F4TE Block
4'' SCAT crank
6.2 Sat rods
-33.8 cc Probe pistons
TFS 11R 205cc heads
(FTI custom cam)
TFS R boxed intake
90mm Accufab
2x GT3582R
T56

Aiming for 800FWHP, maybe more down the track

My camshaft grinder needs to know my desired rev range and said its based on the turbo chargers.

I have followed the calcs on the Garrett website and have come up with a minimum RPM of 2700, Max RPM of 7000 and max turbo efficiency at 4700. This suits me as I don't want to spin past 7K.

Could someone take a look at the attached PDF and see if my assumptions are correct?

Also, are these figures good enough to base my cam on.?

Finally, where do I apply the turbine housing map (attached)?

I have been told "that range is fine, and it won't be the best at 2700 but it will pull hard"- What does this mean?


Do i need to narrow my range down??

Opinions please.

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For perspective, a single gt4718 flows about 42lbs on the turbine side with the .96 housing, 55lbs with the 1.39 housing. That is still on the small side for that engine. A gt55 is first on my list for that engine with the 1.00A/R turbine housing the turbine flows 59lb per minute. Twin gt35's with the .82 turbine housings is comprable (a tough smaller) than the gt55 on the turbine side, and the compressors will reach your goal.

 

Thank you. Apreciate your input.

Could you take a look at the PDF and see if my flow calculation assumptions are close enough?

Also if my compressor map rpm range looks good?

 

Anyone? Is 2700-7000 what I should tell my cam grinder?

 

I would disagree rpm range is dictated by the turbos, the cam dictates that more than anything.

Who's specing the cam ?

And those turbo's will easily make 800...and then some.

 

I'm not doubting the turbos although I think they will start to choke above 7k with the T3 flange used.

I'm getting the can from FTI. Was just wanting to know if I should be telling them that my desired rev range is between 2700 and 7000 based on my calcs...

 

You should have no issues with 800+ hp with that combo, and I don't see the need to spin it to 7k. Personally, I would look at something like 6500 as a shift point, and let the lower end of the range fall where it does..... unless you're looking to favor one end or the other.

 

Thanks for the input.

6500 was always my redline, just wanted to know there is more past this point so I wasn't pushing things to the limit.

Would you agree my RPM range for the can will be between 2700- 6500/7000?

 

I'm not sure I follow what you're saying about wanting more past this point, but no need to over cam.

 

I just don't want to be making the power on the upper limits of the turbochargers.

What power do you think a setup lime this could make? Also what do you think drivability will be like including off boost characteristics? Car will have manual trans...

 

I see no issue with a fully usable 7k, even with a mildish cam. And as far as cams go, you wont need anything drastic to make huge amounts of power.

And as for driveability....where do you foresee a problem ?

It will behave like a 408 off boost so there will be no lack of power or torque, and once on boost traction will be the biggest issue, especially on the street. It should be very responsive.

I know of one guy with a 427 and a pair of the smaller GT35's on the 1.0 AR housing. On a Dynojet he easily makes over 1000hp. As to how accurate the dyno is, I cant comment.
As to how much boost you have at say 2700rpm....harder to say. I'd think it would be a bit later before any real solid boost is being made though.

I'd sooner prefer to see some fast trap speeds, although that hasnt happened yet.

Keep the duration sensible, stay away from overlap and a opt for widish LSA, and it'll be great with a good wide spread of power.

 

Sounds like you know a bit about camshaft selection.

Im not going to tell the grinder what profile to use. Just want to be confident in the information I give him to make it.

In terms of drivability I just don't want the power to kick in all at once. Want to spread it throughout a wide range to make it fun to drive. Also due to traction limits of the car.
I'm expecting to set boost level at 10-15 lb.

Do you think this will be enough?

 

There are people far more experienced than me as far as camshafts go. But one thing I know for sure...there are more negatives from going too wild with a camshaft, than there are staying mild.

If I recall correctly the guy with the 427 was making 1000+ at around 15psi. That power level does sound rather high to me for the boost, but then I never believe any dyno figures.

If you want to soften the hit, which will be largely unavoidable with an engine making so much power. Opt for a control system that lets you ramp boost up with rpm or speed, and is progressive with the throttle too

Whether that's via an external controller, or choose an ecu that lets you do everything...the choice is yours.

I'll be ditching my blower on the next few months and going for twins, although I'm on a 382 ( 4" bore and 3.825" crank ). Still undecided as to which twins though, as I'm in the same boat as you.
I want it to make good usable boost low down, but I also want potential for around 1300hp or so. SO it's either 362FMW's which seem similar to your GT35's, albeit with larger turbine housing.
Or I'll get a custom pair of billet 66mm BW's with the 68mm turbine, so hopefully they'll spool up quickly.

Cam I'm undecided. Initially I'll probably stick with the LPE GT9 that's in my car. But Ive a new block coming, so might swap to an old cam I used, 224/230 on 115LSA.
Or I may get a custom grind, the problem is there are just too many damn options !!

Although I'd be aiming for an upper ceiling of 7500rpm, maybe shift around 7k when I do eventually do the new block and cam build.

 

Do you add the turbine flow of your turbine AR map to the compressor map of your turbo?

For example, what will the GT 3582 flow with a 0.7 AR as opposed to one with a 0.82 AR?

 

Correct I'm after usable power. Also my block is stock so that's why I'm basing it on a limit of 800 HP and 7000RPMax.

What injectors would you guess I'll need? I have bought 65 lb but I think I need to upgrade to 80 lb. I'll be using pump gas 98 RON

 

80's would probably do 1000hp ok, 1000cc would give you headroom.

 

Would 65 lb be enough for 800? Or should o not bother with them?

 

No point in buying something, only to have to upgrade at a later date. They might do 800 at a push if you have enough fuel pump and pressure.

 

I already have the 65lb injectors. Pump will be an A1000 with a 4 litre surge tank. -8 feed and -6 return.

 

No, the compressor map is not affected by the turbine A/R. The two maps (compressor and turbine) are independent.