i'm going to look at an 87 chevy truck this week with a 350 tbi. what are some realistic hp numbers with bolt ons like intake and exhaust? i am new to tbi so any good performance tips would be helpful. thanks?
p.s. sorry if this is a question that gets asked over and over again. i'm just not familiar with tbi

 

I made ALOT of dyno pulls on my TBI 305 in my 1983 Chevy Van. With the stock peanut roller camshaft, TPI 081 heads, 1.6:1 full roller rockers, doug thorley tri-y headers, dual exhuast, and custom prom tuning, it ran pretty well.





I never had too many complaints, even pulling around 5,600 lbs of Chevrolet Van with 3.08 gears even.

http://www.youtube.com/watch?v=Tvay9zOW6hE

 

Hey Drew,

I have a L05 350 like what you'll find in that '87 in my '91 GMC Sierra. I have the stock cam, stock heads, stock intake, stock TB (but little things added like injector spacer, VRFPR). The only performance mods I've made are:

* CAI (worth it, I'd do it first, get a cheap one from ebay or make a custom one with a nice cone filter on the end)
* Edelbrock TES headers (I recommend something else, I was a bit naive and in a weird mood when I bought these, it was an impulse buy)
* VRFPR (make sure it's vacuum referenced and be prepared to drill through your TB and do some 1/8" pipe bending)
* smooth down TBI ridges, install injector pod spacer (worth it, but effect is minimal, but this is very cheap and was very easy for a small, but noticeable gain)
* 3" high flow catco cat
* Flowmaster 70 series cat back (go duals, it's worth it, or better headers with 4" exhaust, but if you go catback, this is a good one)
* EBL Flash
* LS1 e-fans (worth it, cheap HP)
* underdrive pulleys (worth it if you get some used ones real cheap)

Stock, these engines made only 200hp and 310ft-lbs of tq. Not only that, the heads are restrictive and only allow power up to about 3500 rpm, but that will be one killer idle-3500 torque producer if you bolt on the right add-ons.

The EBL Flash probably made the largest difference on my truck second to the exhaust system, but I haven't completely dialed my truck in, I've only owned the EBL a few days, so probably suffering from operator head-space timing. And I put the entire exhaust system on at once. $900 exhaust! So, I definitely noticed the exhaust.

I listed the add-ons I did in order of what I'd recommend. I only place the EBL lower on the list b/c of the price and the learning curve. You should get one though, don't do the chip burning unless you just gotta do the MAF TBI setup. The EBL should put my gas mileage into the 16 mpg area for pure city driving, and 20ish for highway driving due to the lean cruise mode. I'll report on that next week when I have some solid numbers over many miles. Going from Statesboro to Atlanta next week.

In hind sight, I think porting / polishing inside of the exhaust manifolds would have been just as good as Edelbrock TES headers. Not only that, but building a Y-pipe with 2.5" pipe instead of 2.25" like the TES y-pipe would have probably made it a touch better.

I estimate my power somewhere around 230-250hp / 340-360tq at the flywheel. I might go to a dyno when I'm in Atlanta for the holidays and I'll post the results along with MPGs. But, the truck is QUICK from a full stop. It has 236k miles on it, so I don't like to rev it too much, but you have to really get into it if you want to pass someone. Just isn't effective past about 4200rpm.

I haven't raced anything or been to any tracks, but I was behind a Nissan Altima 3.5SE today and I am pretty sure they stomped it, and I had no problems keeping up. We ran pretty close, but I had a little more at the beginning, then they pulled from me a little. We only got up to about 55-60mph. I'd suspect they would have kept pulling on me. About what you'd expect. I'm not the best driver either though, and still getting used to manual transmission. A skilled manual driver or an auto truck and good stall might have kept it closer.

EDIT: just wanted to add, this is what I did, and I can attest to the power. if you use different heads and a stock L31 vortec roller cam (if your L05 has the bosses and is already tapped for spider) or LT1 B-body cam, you'll get alot more power

 

I would use the F/Y car LT1 cam or the Production LT4 cam if you can find it. The smaller cam is barely worth swapping compared to the slightly larger cam.

The swirl ports ARE NOT the cause for the 3,500 rpm fall-off... Mine pulled EASILY to 5,000 rpm and ABOVE without being touched. Its the PUNY, TINY, PATHETIC stock CAM thats to blame.

You are onto something with the Edelbrock stuff not being much better than stock... ITS NOT.... DOUG THORLEY TRI-Y headers are hands down the best headers you can run on a street driven truck.. I have tried 4 different kinds of headers, ranging from 1 1/2" to 1 3/4" primaries and varying lengths. The Tri-Ys just outperformend the others EVERYWHERE and were actually built to last.

This run was the same 305 with stock 187s and a LT4 roller cam... With TPI on it...



I wasn't pulling the boat, but you see what the little TBI based 305 is pulling around.

 

Doug Thorley makes very nice headers, built to last, but with a premium price tag it is a 'hard' threshold (money wise) to cross over. Good to hear from you OM - happy holidays.

//RF

 

Fast355, I had been playing with the idea of a cam swap. According to this:

https://www.thirdgen.org/forums/tbi/...-headflow.html

the 193 heads (what I have) flow a touch better than the 187 heads. So, I suspect I'd get about 275hp, maybe 230rwhp, from a LT1 cam swap in my stock L05 and the bolt-ons I listed, does that seem unreasonable? Even with the Edelbrock headers, I think that's a reasonable expectation especially after I play with the fuel pressure and maybe get a 454 TBI.

I don't know if the L05 I own is new enough to have the bosses tapped for the roller cam. If it's the original engine, probably not. So I am going to buy this cam on my way to visit family next week:

http://www.summitracing.com/parts/CCA-CL12-232-3/

I'll use this one if I can't go roller. What do you think? If I can go roller, I'm just going to use what I already have, which is either a stock L31 cam or F-body 1705 LT1 cam. Do you think that hydraulic cam would be hard to get tuned on a TBI engine with EBL?

 

The 193/191/810s flow a touch better because they are 350 heads.. Your block may have roller bosses in it, it is luck of the draw.

275 HP does not sound at all un-reasonable with the supporting bolt-ons and the EBL tuning.

EBL makes dialing in things EASY.. I had the GM 846 (aggressive Crane Hydraulic Roller) in a 305 being fed by TBI run by the EBL Classic. It idled with 10 in/hg in gear and about 8 with the a/c on. But get it above idle in the 2-6K range with ported 113s (Stock ZZ4 castings) and HANG ON!

 

I've been looking at 113 heads. The Corvette production versions are hard to find and the "ZZ4" versions are expensive. I gotta check the forums better. Did you happen to use the Holley Projection manifold with a 454 TB?

I thread jacked 100%. But, hope Fast's info helped ya drew. Helped me.

You can get some performance from TBI. I was going to go TPI, and think it would have been worth it, but this is my DD and my only truck, so I took the reliability of TBI into account when I got to the point of choosing the direction I was going to go. Easy to modify, cheap plentiful parts (well, it's starting to get harder to find stuff, but still cheap and plentiful comparatively), lots of feedback on this forum and others, good gas mileage. As long as you like the truck it's in, it's worth it.

 

no matter what you do i would suggest building up your lower end i had 327hp in my camaro 305 and spun a rod so before you do anything else make it stronger. if you have a 305 and plan on keeping it they do make a 335 stroker kit for it. but i would just go with a 350