what kinda psi would be needed 4 a 3.5 to run 450h

[no_doz]

how much psi would be needed (with a decent/proper tune) to run a 3.5 non vvt to 450 horse? also what things as far as bottom end would be needed so that the engine doesn't eat itself?

[1988GTU]

Exactly what turbo or SC?

[no_doz]

a very large turbo-i'm not yet sure of the model-one that would allow for a lot of lag if i wasn't running the crap outta it. ive been looking around youtube and finding 300zx's like these:

http://www.youtube.com/watch?v=cdJSKIHzf8U 690hp 28psi

http://www.youtube.com/watch?v=7--2JnReA7k 400hp 12psi

http://www.youtube.com/watch?v=Bysr1LdaGBk 380hp 14psi/560-615hp 26psi

i do realize that a VG30DETT is a VERY different engine from the LX9 but the way i figure-the lx9 has more displacement (always a good thing), and the heads should flow more than that of the 300zx, so with the same psi & a good tune-arent those numbers reasonable to expect-if not a bit low due to the 3.5 having 17% more displacement. please someone give some input on this

[1988GTU]

All just quick opinions without thinking into them*


This one would be very mild for lag and would more than likely blow the tires loose around 3800 rpm's.

http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GRT-TBO-003&Category_Code=GRT

or go with this for a lot of lag and your power goal.

http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GRT-TBO-043&Category_Code=GTB

[Joseph Upson]

how much psi would be needed (with a decent/proper tune) to run a 3.5 non vvt to 450 horse? also what things as far as bottom end would be needed so that the engine doesn't eat itself?

The 3.5 VVT engine would probably be the better platform due to the shorter stroke 3.00 vs. 3.31.

It already has about a 6400 rpm redline which can be bumped up safely after a good assembly balance and valve spring change. GM states it shares the same pistons with the 3900 so you have off the shelf LS1 forged piston options which are available in many different compression heights and dish volumes.

http://60degreev6.com/forum/f96/forged-ls1-piston-comparison-to-3900-t41420

or you can run the stock rotating assembly as is and see what it does, the stock 3800 has been pushed to over 400 hp at the wheels, and we know the stock 3400 will do about 350 hp on 10 psi.

The VVT cam should be reground to more duration and switch activated at about 4500 rpm to extend your power range and still provide excellent bottom end performance as I demonstrated it will work in the video on my latest testdrive although it has to be dyno tested to insure my regrind specs did not defeat the retard benefit.

Otherwise intake and cylinderhead work and a good cam grind with intercooling and water/meth combined should put you over 500 without having to run so much boost. Lighter pistons and/or rods are just icing on the cake.

I believe the engine is good to whatever the stock naturally aspirated 3800s have been boosted to which should be easily in the 400 plus range. I believe they should be limited to 7 k tops for the sake of flywheels and auto trans. For some reason the VVT engines have about a 400 rpm higher rev limit than the non VVT 3500.

[no_doz]

now THAT is a good in depth answer-and by ls1 pistons do you mean that the 3.9 and 3.5 vvts use pistons interchangeable with the ls1? also do they make cams for vvt's with different specs than stock for each (the norm/vtec lobes) rather than just 1 overall grind?

[RedZMonte]

450hp is a pretty strong number... is it gunna be a drag car or a street car? Honestly to get 450 hp especially to the wheels is gunna make it bad for the streets and you will have issure with reliability (tranny and whatnot). It will take a big turbo and will have a good ammount of lag. for a street car you can have a safe 350hp and still walk most every car on the street. you will need to do the calculations and graph it on a flow chart.. I would run a Garrett GT series or a Borg Warner turbo... depending on what kind of power your looking for they make ALL KINDS of different turbos. Also you will want a well designed setup, Tubular turbo manifolds, mandrel x-over, 3" down pipe and 3" exhaust.

Im currently thinking about redesigning my setup with all of the above and a "Twin Scroll" divided exhaust housing turbo for better spool up. It will take alot of work and allot of time tuning..

S

[Joseph Upson]

now THAT is a good in depth answer-and by ls1 pistons do you mean that the 3.9 and 3.5 vvts use pistons interchangeable with the ls1? also do they make cams for vvt's with different specs than stock for each (the norm/vtec lobes) rather than just 1 overall grind?

They all share the same cylinder bore, depending on what piston you go with you most likely need to have valve reliefs cut but you can buy the tool from Lindy Tools to do that for about $115 that works much better than the tool available for rent from comp or Isky cams which ever has it. You may also need to have your stock connecting rods rebushed unless you go with pistons that have the pin bore about .001-.002" larger than the V6 pin, you would only need your current bushings honed to the larger pin diameter which wouldn't take much.

So far I've had custom bushings made for my stock rods since I have .927 pin pistons, they ran me $15 each, I was quoted $85 for installing and fitting. Then there's $250 for balancing. The end result is pistons that are lighter by about 50 gm each than stock on a balanced assembly that will spin faster safer. You can also aim for a lighter rod but you would incur more expense and with a short stroke I don't think it would be necessary anyway.

You should stick with a regrind of the stock cam to whatever specs you want within reason. Delta Camshafts did mine for about $85. I would suggest not tampering with the LSA and just increasing duration to about 220/220. Although the non VVT cams can be adapted to the VVT motors, my concern is that the lobes are not as broad as those found on the stock cam which will limit how aggressive lobe openning rate can be to take advantage of how well the heads are capable of flowing with the bigger valves and taller runner ceilings.

I believe all you need is a port and polish job, LS6 springs and a camshaft regrind along with about 15-18 psi and you should be in la la land with more power than is practical for a daily driver.

[RedBird]

why is this in the DOHC section?

port and polish, gasket match, upgraded valve springs, and a half decent set of turbo headers should push a non-vvt 3500 past 350hp on about 8psi with a correctly sized turbo.
midnight did 358whp in his cavy(5 speed) with a 3400 with those same mods, at(i think) 9 or 10psi. so the same stuff on a 3500 should be close to 400hp, or thereabouts.

[timg]

The GT35R would work well. They've done over 600 whp in smaller motors. The GT4088R would allow you to do it with lower boost, but will have more lag.

Expect to need 15+ psi of boost, if not 20. That's not likely to happen on a stock motor. 15 psi of boost should roughly double stock power if tuned well and nothing breaks.

Tim

[timg]

I wouldn't use any GT2x turbos unless you're using a pair of them. Their nickname even on 2 liter 4 cylinder engines was T-2-small.

Tim