Was asked what could be had out of a stock base quite awhile ago, and came across this thread http://www.corvetteforum.com/forums/...post1543919697

Had to find out for myself so the answer is YES it can be done but it wont come easy;getting ea port to be fairly consistent is tricky and can consume stupid amounts of time. Start paying for bench time it really adds up

(Know some of you may have btdt personally I couldnt find anything on it just a few random claims so maybe this thread is a waste for some)

In fact over the last yr Ive done this with the GM tpi, Accel, Superram, LT1 and LT4s flowing them quite a bit just to see for myself just havent put it out there yet. All I can say is when you see a claim say "prove it".Unless they own a flowbench they cant, it would cost them more than what they could charge ya to do it.


This one saw the flowbench quite a few times to get them all within an acceptable range ;there just isnt any more room to go on without busting holes and shocked I didnt on this one.

With a better fixture (I simply didnt have time to improve on)scratching out 250 is a big maybe.

There is still the FIRST option which for the money is your best bet if youre a LTR fan. I understand the "E" intake will be obsolete soon so options for these are getting slimmer unless one uses another style altogether

Anyways I never saw a concrete answer with anything to back it up so mystery (for me anyway) solved.

No fancy pics we all know what a TPI looks like lol

 

Darn good work Ron. What size opening do you have at the runners?

 

Thanks Alan
They are a big 1.75 slightly oversized.Not quite 1.8 Id have to break the mic out its been sitting around here fora few mos

1205 Felrpo head side

Will be taking measurements inside before this one goes to help dup. another should I get the itch ....actually a port mold would be even better. Ea one I do now I record these stats every inch and serial # them.

More of just a fun project think this would be cost prohibitive for someone to have done

Think if I ever got another TPI car it'd just be a driver. Keep it 100% stock save for a small cam and make the most out of what was there just for kicks (ie heads int). Buddys got a mint Yellow 85/6?? Iroc Id love to have.

 

That is pretty darn good. I wonder how the Accel runners would match up? Something with a 1 7/8" od tube would do the trick and pass for stock to most people.

If you know someone with a machine shop it is not all that hard to make up the runners. All you need is some 3" radius 1 7/8" diameter u-tubing and some 1/2" thick bar stock plus some money and maybe some more money.

 

:sigh: dont get me started I really need to keep my day job haha
See youre just as sick; love stock looking parts that work

About 10 yrs ago I bought a 89 C4, knew the TPI was a turd and read if you ported them you could pick up something. Was going to put a 400 in front of one

Quote from the only place I knew at the time that would give me a proper portingjob (not a scuff and shine) was $800 for the base. Now we know why....anyyway the bug started there
Kind of a research freak anyway

The wheels still round

 

Thanks for posting your findings. I had a homemade flow bench back in the late 80s and early 90s. No way of telling actual flow, but I could tell when I was making improvements or not and got a good feeling for what worked and didn't work. I always felt like I could get a stock base to flow around the 240cfm mark, right at or close to an out of the box aftermarket intake - I was also gauging that by knowing a stock extrude honed base flowed in the 250cfm range.

Getting the base to flow is one thing, but the bad transition points are another when bolting on the runners. The last few TPIs I've done a little off-set porting at the runner to base transition - I'm sure the base flow is down from a full "center port", but I do believe that with the runners bolted on the combination of runner and base will flow better. Seeing how I don't even have a homemade bench anymore, I can't prove it, but my semi-educated guess would be it does. Plus, it does seem that these off-set ported systems (with fully ported, not welded SLP runners) tend to mph a little higher than what I typically see on the web.

Anyway, thought I would share that little "trick" since it looks like I'll never port another stock base again. If you can't do your own porting, or not comfortable doing an easy self porting/clean up of the stock base and mild porting to a set of SLP runners when doing a mild "bang for the buck" build,, it's best to look at something like the FIRST if you're sold on the long runners. Like you said, it takes WAY too much work and the cost is prohibitive to pay someone that knows what they're doing to port a stock one.

 

And more money and more money. When I think of what I might have done in the intake area with what I spent in money and time(porting for hours and days) on this TPI of mine, and I still play with the idea of having larger tubes made. More money into a system that will never really be what I want it to be. Darn it all. I have had alot of fun with this long runner TPI and still plan to see what this intake and heads will do on top of a 406, then it's on to something with much shorter, straighter runners.

Still anxious to see what the Cross Ram has in store for us(hint hint).

 

Yes thats a heck of a project hes doing isnt it!

If anyones messed wiht the new LSx truck intake the way those runners are shaped and tapered would be the hot ticket...or close. My god can those move some air! With some work in the right places they go even more.
Alan is correct a better runner is of importance to make it work;dont think Im going to tackle that . SR runner doesnt hurt them much if at all if done correctly

x2 my original goal also. 230 wasnt too bad but the time to get even a few more to this point and be close in flow was just stupid; Between time and paying for the bench agin and again I started questioning my sanity.

Dont know if i could even sell it and feel good about what to ask as I dont have a TPI car right now.

I have looked into CNC but anyone with a machine wants it running 24/7 thats just not possible plus the $ for the program. Maybe 20 yrs ago it could have been a worthwhile idea. Fun stuff anyway

 

Edit; double posted accidentally