I’m evaluating my options now that the cam bearings are bad in my 72k mile 89 vette engine. I know I’ve gotta finish pulling the engine to see what the main & rod bearings look like as well as the bores & crank. So here’s my question; is there a way to make a stroker kit work with the stock TPI system for now, & then later upgrade the major components?

I know to maximize the stroker I need better heads, bigger intake, throttle body, fuel injectors, fuel pump, etc. However, if I have the short block disassembled & have to have some work done at the machine shop, I’d love to be able to do the stroker bottom end kit 1st. Put it back together & run it for a few years before doing those other needed upgrades. What say ye?

Just to let ya all know I have already done a clean up porting of the intake plenum, runners & base as well as a little bit of the intake head port entrance. So mostly stock. The cam I already have & was going to use is the TPIS Super L98 single pattern 220 dur & .427 lift w/112 lsa. I could always add 1.6 rockers if absolutely needed or perhaps get a different cam.
Thanks!



Just worked the first inch or so to even up all the head ports

Clean up & matching to gaskets

Took out the ridge on both ends & made sure gaskets matched up well

Knocked down the major obstruction at the front bottom then opened up the bores better

Cleaned it up but focused on removing some of the bend obstruction at the head side.

 

Sure it will run good and you can upgrade later but know youre leaving a ton of power on the table.
You can take a ton of material out of the stock base, getting it to 230cfm is realistic just takes lots of time.
. When youre ready you can open up the ports on your plenum, I just got rid of the divider wall all together. Same in front
If youre open to other intakes I like the idea of a converted LT1, cost effective and a nice boost in power. Still looks stockish, easy to port

 

CV67,
I have heard that before about removing a lot of material from the intake base. However I’ve not seen any specifics about what size one can safely enlarge the intake ports to, (like a specific number here & there kinda thing). Not knowing how much I really could or should remove I tried to error on the side of caution to open things up some while trying not to kill the port velocity & lose low end power. Additionally, I was set to use the stock FelPro plenum & intake gaskets since I wasn’t planning on changing to larger runner tubes.

 

Personally, IMO, if you're budget limited I would perhaps just leave the TPI intake on there as is, not even do the work of porting and polishing, and put the time, effort, and funds into building the best stroker long block you can. Then down the road you can swap intakes. This would mean that you'll have to thread the sort of proverbial needle because the right heads and cam for a 383 with a factory GM TPI will not be the right heads and cam for a 383 with a Miniram.

The "right" heads and cam for a factory GM TPI might be close to the actual right heads and cam for an Extrude Hone TPI setup, extrude hone Arizona Speed and Marine setup, or a FIRST TPI setup.

 

Go ahead and do all the internals as you will want them. Everything else can be replaced without pulling the engine when you are ready. Sure your gonna give up power till the build is complete but its either this way, wait till you have everything, or assemble a new engine and swap. With the stock TPI unit i wouldnt worry about a different cam or 1.6 rockers, put that money toward a new intake and heads for later on.

 

Yakmastermax, the pictures I posted in my opening post are of the things I e already done. Not ideal for a 383 but helpful for my original plan of just doing the cam & springs upgrade. I already have the cam sitting on the shelf & was all ready to install it until I found the bearing issue.

I guess my big concern is can & how one can do the stroke kit with the stock heads & the intake as I have it now (pics in 1st post). Will it need an ecm worked on? Can I use the new “stock” fuel injectors I already have? Are there specific things that no matter what I’ll need to do to get it to run?

 

pcm for less can get you a tune (mail order), probaby have a file on hand that will work.
Far as losing velocity you wont.

OP if you got some oversized TPI gaskets from summit (Mr Gasket) you could use that to size your base.
Then swap out for larger runners when you get them. Pretty sure the stock runners would seal but would have to double ck.
Wanna say 1.75 or 1.8?

 

My concern on this is that with the midrange torque spike of the TPI intake, you'll need to build a considerably lower compression ratio (~9.5:1) than you would with a more normal, short-runner intake (11:1). And then when you swap to the shorty intake later you will have a low-compression engine that hurts power and economy. I think your stock L98 heads have a 58cc chamber, which will just exacerbate the problem. I'm not sure of a good workaround for this unless you can go ahead and build for a planned 10.5:1 CR with aftermarket heads and then calibrate your spark tables to pull a ton of timing around the torque peak you get with the stock heads and intake. I really don't know if that's safe or feasible though. So to sum up, the problem is that you can't build a short block that's optimized for both the stock heads/intake and a good-breathing aftermarket setup.

 

My SCR is 10.2:1 using long runners (It's 8.3 DCR). I'm using 56cc chambers under AFR195 heads with a 383. Building high compression is a matter of good quench...and making sure "hot edges" are eliminated from the build. I'm not the only one whose built this kind of setup either. mrc24x built a 10:1 setup in 2007 (using TPIS-ported 113s). I sort of modeled mine after his build -- which can be appreciated in his video.... Both of us use long tubes with a stroker. There are others.

Max CR will be 1pt lower for iron heads.

My timing is typical for AFR heads. I remember Jim Barth posting that 31-deg is fairly typical for max timing...which is what's in my setup. Like the stock, lower-compression timing table, I removed 1-deg in 1 cell near 3600rpms. The same can happen from any intake/setup. When you get away from the OEM cam, you can raise torque peak 800-1000rpms. 3600 is typical.

If it matters, I'm using 20cc dish pistons...to stay in a reasonable CR. One manufacturer website believes they resist detonation best because the "flame ball" is consolidated within the dish. I never asked Matt (mrc24x) is he was using dish pistons too...but probably so since he used TPIS ported 113s....which are also 58cc (or less). He used a hotcam. I used a hair less duration with more lift....meaning the cam doesn't have to be big (to "bleed" compression).

In general, the difference between 10:1 and 11:1 (or 1pt compression) averages 10hp ... when looking at results. When talking to MMiller 2-3 years ago, his MPG is 1 mpg less than mine. Of course, his displacement is 13cc bigger. FWIW, I'm thinking 10.5:1 SCR is doable. (My quench isn't in the ideal range -- though good + DCR isn't maxxed out).

There are ways to build a stroker in stages though I would suggest "tweaks" in the build will favor your direction. 6" vs 5.7" rods (for example) favor hp vs torque. Header design can do the same...cam orientation too. For street engines, the differences can be subtle. There are bigger considerations -- like differential ratio. Short gears favor short runners and visa-versa. To me, this is decision #1. If gears aren't 3.33 or higher, a torque build may produce a more enjoyable street car.

Note: My runners retain 75% of original length...meaning 25% of divider is removed.

 

Diff is a 3.33

 

Same as mine. That puts you in the ideal place of being able to build a 383 (longtube) TPI, then convert to a shorter intake later -- if you like. I'm certain the stock TPI will be fun over a 383 but stupid peaky. You'll be frustrated with a lack of "run-out". In the long run, you'll want something midrange or shorter.

I have a hogged out SLP setup myself. Have had it since 2010. Recently, I revisited my options. I've kept an HSR if I wanted to try it (under my hirise hood). Ironically, I think I can get close to another 30hp by removing 2 more inches of the SLP dividers. Plus, I've always wanted to maximize them with honing -- though I spent tons of time on them myself. I'm also blowing exhaust through a bit of a straw...leaving me about the same amount of improvement on the back-end. To be honest, it's kinda nice knowing smaller changes can improve your setup even more!!!

BTW...I edited my prior post to correct my DCR (guess I remembered it wrong) and add a cool video of a long runner 383. Matt's car is a 383 with TPIS intake, TPIS headers, TPIS ported 113 (stock 89) heads, hotcam, and 10:1 compression in a 355 PACE shortblock.

My build is similar....AFR 195 heads, 214/214 .544/.544 cam, VT 1 3/4" headers, 383 4-bolt Chevy block, with ported mega-ported SLP intake. If I remove 2" (more) inches of intake runner divider and convert to bigger exhaust, I should come out with 20rwtq/50rwhp more than his setup. If I converted to an HSR, I'd probably lose 20rwtq, shift it 500-600rpm higher, but gain 70-80rwhp. When driving a street car, it's awfully hard to consider giving up torque...for the more occasional 5k-6k rpm fun.

I post these options as something you may also consider some day. Plus, the video gives you a clue where you might be headed!

 

This is a very good street set-up. I have the TPIS Big Mouth, the SLP runners were worked by removing a good portion of the divider and the Plenum was ported as the were the 88' 113 heads. Then all was sent off to extrude hone to so their magic. Its all on top of a stock 350cu in bottom end. with a CompuCam. I think 2040 or something. My 86' is a 4+3 with 3.08:1 in the Dana 44. Has more torque than most but can run easily up to 5,800 rpm's as the power curve is flat from about 5,200 to 6,200 rpms my MSD6Al box has the 6,200 or 6,400 chip but i try to shift by 5,800 so the shift drops it back on the sweet spot. After this work my TPI no longer had a wall at 4,800 rpms.