RedHawkLB9

hi,what kinds of things can i do to make tpi flow nice only up to 5000(dont need higher) since it peaks at 5k on a 350ci...i already have a vortec base..and on a tight budget...can i just port the snot out ouf the stock runners and plenum,vortec base?
thx bill

hotrod7687

I'm guessing since you have a vortec base you already have vortec heads? If you do that should have been a nice jump from the stock heads.

I dont know about the vortec base, but theres not a lot you can do with the stock runners. They're very thin from the factory and doing anything but poilshing out very minor casting flaws will have you cutting through the wall of the runner. I learned that the hard way

1987ZTPI

Port the plenum, new runners. SLP, EDELBROCK. First tpi systems work good from what i hear but they go for $1000. LTR setups like the tpi aren't ideal for high rpm engines but you can make them go as high as 6000rpm and still make good power. But it's not cheap.

five7kid

iTrader: (14)

No. The issue is the length of the runners, and porting won't change that. Can't really port the runners, anyway.

RED86Z28

Everyone always says they wont pull past 4500 but mine pulls strong till at least 5200.

RedHawkLB9

nice...is yours modded at all?....and yes..vortec heads

RED86Z28

I have edelbrock runners.

Fast355

iTrader: (2)

My engine 350 CID Vortec TPI EASILY pulled WELL past 5,000 rpm and made power till around 5,500 rpm with the STOCK intake runners. Torque was falling off, but the HP curve was FLAT from 4,500-5,800+.

You need prom tuning if you are not pulling 5,500+ RPM with ease, even with the factory L98 cam. As long as you have a good exhaust with GOOD headers, you should be making power to 5,500 rpm all day long.

I have TPIS oversize long tube runners and partially siamesed SLP old design runners. I will be trying both soon just to see which runs best. Honestly I dout the SLP runners are going to be the best with the stock 1,600 rpm converter and 3.08 gears, but the TPIS runners should take advantage of the 6,000 rpm power potential these heads and the cam have.

Fuel Shut-Off is 5,800 rpm in this video.

hotrod7687

Thats with a completely stock engine. With bolt-on's like headers, intake, exhaust, etc you can get a little more out of them. Still, its nowhere near the gains you would see with another intake system.

What kind of gains did you see when you installed the vortec's? I'm curious because I always thought about doing that on my 87 formula.

tony_cogliandro

iTrader: (3)

what is the device attached to the valve cover with what appears to be a spart plug wire attached to it?
is that your shut off?

Fast355

iTrader: (2)

Older Accel Super Coil

Shut-off device is the 7730 ECM.

five7kid

iTrader: (14)

Exactly. You weren't making any more power above 4500 RPMs.

"But my ET is best when I shift at xxxx RPMs." That's a different issue. You should shift so that the engine is at peak torque in the next gear, which means you might need to shift at a different point 1-2 than you do for 2-3.

Fast355

iTrader: (2)

I agree 100% with you, its just not like these guys make it out to be. Just because it starts to flatten out above 4,500-5,000 rpm, doesn't mean it just stops pulling and falls on its face, it just quits pulling harder with more RPM though its still pulling strong. The way it sits, my WOT 1-2 upshifts are setup for right at 6,000 rpm and the 2-3 upshift about 5,600, thats with STOCK GM Long Tube Runners, FWIW. I have run 5,700 rpm with the TCC locked in 3rd gear with 3.08 gears and 29" tall tires, pushing the BRICK into the wind. Run the numbers through a gearing calculator if you want, but I'll save you the trouble and tell you, in theory, I could have been going 134 mph, if the numbers aligned right.

LMSkyliner

iTrader: (1)

If you go quick you can get it for $825 https://www.thirdgen.org/forums/grou...-intake-2.html

Plus it comes with more than alot of systems do so its worth it IMHO.


other than that, just get new runners and base and start porting.

creese187

with 17 inch long runners your never gonna make good power at 5 grand, instead you need to get shorter runners, like how gm did with the lt1, you may loose a little torque, but the hp will rise accordingly, the long runner in a tpi is the main cause while it wont make power at 5k plus