3500 Power questions

[2.8-350TBI]

Okay, so I am out to buy a 3500 for my new blazer.

I still plan to autocross it, so the 4.3 will be out and a 3500 swapped in. But I will be doing major work here.

3500, 4l60-e, and awd with a bravada/astro awd system.

My goal is to make 400 hp, and it looks like I will be using a 7427 pcm.

Practically everything will bolt on but the motor mounts.


Now having said that. What kind of prepwork is necessary to EFIICIENTLY make 400HP?

IE: Bottom end work, top end work, cam, valvesprings, and turbo setup.
Any input will be appreciated, as always

[pocket-rocket]

I've been told Astros like to eat front diffs. Might want to stick with the AWD from an S10 based vehicle (Bravada, Envoy, Blazer, ect.)

[2.8-350TBI]

I've been told Astros like to eat front diffs. Might want to stick with the AWD from an S10 based vehicle (Bravada, Envoy, Blazer, ect.)

I will keep that in mind.
It will most likely come from a first gen bravada. We have quite a few in my area. I see about three every day and for some reason I see two new ones in town now and 6 or 7 in the jy.

Im mainly concerned on how to make 400 hp reliably and efficiently on the 3500. I dont plan to push like 20lbs of boost down its throat, so I am in search guidance here.

School me.

[geoffinbc]

Do you have a 4X4 already? If not you will need at least the frame to accommodate the AWD transfer case and front axle.

[2.8-350TBI]

Do you have a 4X4 already? If not you will need at least the frame to accommodate the AWD transfer case and front axle.

No, not yet. I am aware that you need a 4x4 frame. Im thinking a 2 door 4x4 frame from a tbi truck should work well. And then convert the front end to qa1 coilovers

[bob442]

I wouldn't imagine you would need to swap frames, if you do, put an IRS in the rear.
As far as 400hsp, assuming thats crank HP, the 3500 is a bit unexplored, so its a black and white situation. I cant rememebr who, but they had a turbo 3400, pushing 20psi, and made 368 WHP? i think i'm correct on that.
Anyways, if you want to build a 400hp motor be prepared to spend alot of money to make it reliable. Thats not saying that you couldn't throw in the bare essentials and meet that goal, and never have an issue, I'm also not saying that stock internals will hold up forever, but eventually, somethings going to give after some abuse. So machining SBC rods, Diamond pistons, cam, ARP bolts, P&P'ing, your looking at almost $2500-3000. Its the way i would go however if i was going to shoot for that.
Just start with a good block, all machined and ready to go, put down a budget, and put the money where it needs to be, do ARP bolts, some sort of aftermarket piston, cam, pushrods, springs and retainers, and if the budget allows, get it ported by Ben so you wouldnt have to crank up the boost as much to achieve your goal. Remember, PSI is a measurment of pressure, if your ports are small and rough, you'll be pushing a higher pressure to achieve similar power goal, for instannce, 20 PSI would make 350hp on a stock topend, but 12-15 PSI would net the same power on a ported and polished top end. That is not realistic figures how ever. If you have a lower PSI on the intake, it will be easier to match to the exhaust side and achive a 1:1 PSI goal for a smoother, more realiable boosted setup, less chance of boost spike.

Lay down your budget after you have the essentials that you need, then come back to this topic, and i'm sure everyone will point you in the right direction. Also, be prepaired to drop atleast 2g's on a transmission and custom tourqe converter to take advantage of your power curve. At 400hp, it will be worth every penny.

If you take my advice on a IRS, look at a 2003 mustang rear end, it will be extrmely easy to install and has all sorts of hosts for aftermarket. If you cruise around enough, you could find a built up rear for probably 800-1200 with posi, bushings, supports, and 4.10:1 gears, brakes, whole 9 yards. If not that then a C5 or C6 is the next best option, but will cost more to simply purchase.

[pocket-rocket]

The late model T-birds also had IRS. I don't mean the ones that came back from the dead, I mean 95 96ish.

[Mars]

you can have a damn reliable setup around 400HP using pretty much all stock parts. I have a blower my car put down 383 to the tire, runs 11's on stock 3400 pistons, head bolts, rods, crank, not much has been changed on my engine at all (cam and springs) It goes to 7100+RPM. You'll want to concentrate on transmission goodies more than engine parts if you want a reliable 400HP. A 3400 will make that power at 15 psi with a good tune. You could always freshen up the bearings and that, but I wouldn't bother with pistons, rods and stuff till you want 550+.

I will be pushing a 3500 to the limits this sumer. (they cost 250$ here for 20,000 miles). So I don't care if I blow it up. 65mm turbo and I'll be giving it a hard time, we'll see if it comes back for more.

Best thing about a stock motor, you blow it up, goto junk yard, swap in another stocker and you're back on the road for 500$. Whereas something goes wrong with a built engine and you're down $3K.

You realise you can't use the 4l60 that's in there right ? Different bellhousing... I dont know if you could rock the same TH350 - metric V6 adapter plate that I have on my camaro though ?? hmmm

[2.8-350TBI]

you can have a damn reliable setup around 400HP using pretty much all stock parts. I have a blower my car put down 383 to the tire, runs 11's on stock 3400 pistons, head bolts, rods, crank, not much has been changed on my engine at all (cam and springs) It goes to 7100+RPM. You'll want to concentrate on transmission goodies more than engine parts if you want a reliable 400HP. A 3400 will make that power at 15 psi with a good tune. You could always freshen up the bearings and that, but I wouldn't bother with pistons, rods and stuff till you want 550+.

I will be pushing a 3500 to the limits this sumer. (they cost 250$ here for 20,000 miles). So I don't care if I blow it up. 65mm turbo and I'll be giving it a hard time, we'll see if it comes back for more.

Best thing about a stock motor, you blow it up, goto junk yard, swap in another stocker and you're back on the road for 500$. Whereas something goes wrong with a built engine and you're down $3K.

You realise you can't use the 4l60 that's in there right ? Different bellhousing... I dont know if you could rock the same TH350 - metric V6 adapter plate that I have on my camaro though ?? hmmm

I see. I plan to have a good purpose ground cam and matching springs, but im trying not to do anything to the bottom end.

There are 4l60 bell housings in the narrow housing/left side starter you know? 3800 f-body. I already found one

And thanks for the info. I just need to find a cheap 3500.

I hope the bottom end will take 400. I dont plan to touch the bottom end. Just a good cam and some gasketmatching and port smoothing and lets go.

[SappySE107]

ARP rod bolts might be a good idea. Crank scraper wouldn't hurt.