Seeing as how the L31 is the same engine aside from the camshaft as the Ram Jet and the 330hp 350, the engine is cable with a cam change. The biggest problem reaching 330-350hp with your plan is the stock tpi system. Put a stock TPI system on the strongest 350 and it's going to choke it down. That's TPI for you.

 

 

 

It's been a few years since I researched it, but I would've said about 275 to 300, so I'd say you're about right. I've always wanted to build a budget vortec TPI. L31.....slightly bigger cam....basic "stage 1" porting work, smooth the casting, port matching etc. etc. but not go crazy, stock TPI, and really see what it'd do.

.....as for the TPI choking down power, keep in mind that for a mild 350/stockish type build, I really feel that any loss of dyno'd horsepower is made up with daily driven useable power band. Meaning it's very fun, and torquey.

 

Oh I'm not saying it wouldn't be fun to drive. I'm saying if you go into it thinking you're going to get 350hp on the dyno, or be pissed off, don't blame me when you're disappointed.

 

given the apparent healthy demand of vortec TPI basis, you'd think there'd be dyno charts out there...

 

...I think a lot of guys just wanna build and engine with some parts they have (vortec heads) and give it a little more oomph than stock. Lots don't care about the numbers.

 

I hope that's the case, and not being facetious, it isn't that the numbers are a bit too sobering

 

Hey guys, I'm going to piggyback off this forum... I've got an '89 Trans AM GTA just picked it up yesterday for pretty cheap. It has a spun bearing so I've been looking at replacement options. Based on what I've read so far, it sounds like the L31 paired with Vortec/TPI Intake base (links below) are the most straight forward to swap in and get her rolling down the road again. It doesn't look like this forums OP is still active, anyone have any further advice for this setup? Looking at making a purchase within the next week or so. Thanks!

https://www.summitracing.com/parts/n...display-detail

https://sdparts.com/i-23896057-sdpc-...SABEgKtA_D_BwE

-RtR

 

I just finished the L31 swap with the Vortec baseplate and it is pretty straightforward. One other thing to watch for is that the L31 is made to work for several different vehicles so it has spaces for sensors that our cars don't have. One example is the crank sensor. The holes for these sensors have to be capped off, just another thing to remember when fitting things together.

 

Tilly, Thanks for the confirmation and appreciate the heads up on capping. Btw, did you do a new crate motor or snag one from a used vehicle? If you did the new motor, do you mind sharing where you purchased it from?

 

 

Thanks Ty! I'll check them out. And yeah it was the red one on Raleigh's craigslist. Really solid body underneath and only a couple minor rust areas throughout the rest, which is what sold me. Plus the final price left some breathing room to find a new engine.

 

I got the crate motor from Jeggs. Hope everything goes well with your ride!

 

 

Got more information on this dealer? Cheapest I am seeing is around $1900.

 

I believe the name was Radley Chevrolet. I’ll see if I can dig up my invoice when I get home.

 

the stock l31 with the camshaft from the sp350/357 vortec(also simply add ls6 valve springs and comp retainers)
will give you 357 horsepower and 406 ft lbs.its cheaper to buy the l31 crate motor and stab this cam in yourself and save $1500

i just bought a used(but extremely clean and great running) l31 and this cam myself and im gathering up the specific parts to swap it myself as well.
ls6 valve springs are $100 on s u m m i t and the retainers are under $100 canadian,25% less for americans(lucky stiffs)

 

Not sure what the lift of that cam is but if you’re trying to squeeze what you can without machine work, also get the appropriate keepers/locks. I saw a c0.03 increase with some comp keepers over stock l31 ones

some have also got extra lift from different valve seals

 

I just picked up one of these
https://www.summitracing.com/parts/nal-12670966

 

Seems a bit pricey to me.

 

The lift of that cam was designed to work with STOCK L31 heads when run with a 1.5 rocker ratio.
The lift is 0.473" on both intake and exhaust.

 

The T-5 will take it as long as you don't dump the clutch.

 

Very interesting, all.

 

I was reading about the L31R in Summit/Jeggs, for my '89 IROC Z Vert. Currently a LB9 305 TPI/ AT. . I'm thinking it's cam has too much lift and duration, to pass Ca. SMOG . Anyone?