during a recent dyno session, I engaged a aquantance in the virtues and faults of TPI while comparing a stock TPI camaro dyno run with that of a rare stock 5.0 mustang. we agreed that the TPI could add torque to just about anything 305 or larger but upon running out of air it would be pointless. but considering the flow numbers of stock (this might apply to mildly modified TPI intakes as well), could it be able to sufficiently supply a little motor like a 283 to near or above 6000 rpm? we though it might. the conversation moved to the discussion that there was built, a partner or brother head to the L31 (1996 vortech 5700), for the vortech 5000 a 58cc head with 1.83" int X 1.5" exh. valves that has the same ccombustion chamber design, and similar but lesser flow charachteristics that might do a 305 TPI (with its bore size just over 3.70") well using the SDPC vortech TPI lower, but could work very well with the 283's (bore at just over 3.80"). 283's historically have had small chaimber heads like 54-58cc's so this seems ideal to this never to be built (by us) but soon to be over discussed engine. then we went to camshaft selections, we figure that some of the non roller stock TPI 305 (85-86) cams might get the job done with the low cam requirements of this intake and this size of displacement motor, but we agreed on the smallest compucam from crane as the "no nonsense" choice. then I got to talking to him that this would be a pretty cheap motor to build but we both agreed that it might only make the power and maybe torque of a mild or stock 350 (probably like carburated) but would get great gas mileage and have beautiful emissions ( due to the small bore). then I took it a step further, I said, "what about turboing to bring the power up?" he said what is the "cc displacement" I said, "using the rough 60.5 cubes per liter in my head I get just over 4.6L (imagine that)" he says, "half of that is 2.3 and you could try a pair of the 2.3 ford turbos the A/R is close." and I said "HHHhhhmmmmm?" (insert your 2 cents here)

 

I don't know if the lesser cubes would really let the TPI rev much more. The big problem (the way I understand it) is the length and "tuning" of the runners. But then again, the physics is way to complicated for me at this point so maybe it would rev.
The turbo's would probably work if the .48 A/R versions were used. They've been used on several 5.0's with a lot of success. The .63 A/R versions would probably give too much lag.
Thats my 2 cents, don't know if it helped any.

 

n/m......cant give away my secrets this early in the year

 

he-he

 

I was pondering this....

350 block and use a 3.00 stroke baby LT1 crank
5.7 or 6 inch rods and forged pistons.
LT4 intake(JM convert) with fastburn heads and hotcam.
.030 over should put it at 306 cubes.. any thoughts?

 

sounds like Steve Cole's (from TTS) 93-97 camaro, and the one that Mark Mcphail built for chevy at the proving grounds.

 

The turbos would help overcome the restrictions of the TPI. The gentleman that had the 305 running 9's with a turbo would add proof to this. I think if turbo's were an option, I would stay with a 350, or even a 305.

 

Think of the TPI as restricting max hp (airflow), not rpm. A large motor will hit that point a lot sooner than a small displacement motor. In that case, yes, the TPI won't be a bottleneck on the smaller 283 until a higher rpm. It's great as a huge torque number intake, so for rock crawlers, street rods, etc, you can't beat a TPI for the max torque.

The (almost) only reason to go with a shorter stroke is so you can spin higher rpms for more hp (since you'll theoretically hit the same torque curve, but at a higher rpm, so the "force per cycle" occurs more often = more hp). The bottom end can handle a certain amount of force before self destructing. If you've got a bottom end that'll handle 6200 rpm in your 350, shortening the stroke to 3" should give you another 1000 rpm or so headroom. At that point your hydraulic valvetrain can't keep up, and it's time to go to a solid cam with stiff springs. The best bet is to build the engine as a unit, with a thought out combination. Come up with a HP number and max rpm, and work backwards from there. If you need insane HP, you can get it by spinning rpms, or "enhanced" induction (i.e. nitrous or turbo/super). If you want to keep the bottom end sane (not a $10000 bottom end) you'll need to limit rpms to something reasonable, but then you don't need high dollar super light parts. It's cheaper (and I'll dangerously say - more reliable) to add additional boost than it is to spin another 1000 rpms. For most folks looking for hp bang for the buck, a std run of the mill 355 with forged parts and a power adder is a pretty safe bet. I've rambled enough.

 

I love cubic inches, the only reason I wont go big block is because I have too much invested in small blocks and running gear. But in theory only this seemed like the low buck no brainer experiment. many guys like me have the stock TPI units laying around (having been replaced by something better). when you call most big city wrecking yards or when I talk to my friends that have running small blocks lying around they are usually 283's because all the good fodder has been grabbed up. the 305 19# injectors would work fine and any TPI or HO 305 head you may have lying around was not only designed for a small bore engine (305,283 & 307's) but is superior to just about any 283 head ever produced (even the "powerpack" and "283 fuely") especially the centerbolt style which are often used in conjuction with an "unported rule" in IMCA modifieds for circle track. the reason I brought up the turbos is because every on is always looking to build that junkyard twin turbo setup and the 283's 4.6 liters are really close to 2X the size of the ford turbo 2.3. and you could if budget allowed add the few improvements I listed or have them as future mods. If you blew up a 283 in the learning process then drop another $200 to get another wrecking yard one.

 

checked out Steve's 302 camaro, nice 400+ horse, but based off a LS1. Couldnt find much on Mark other than some bio and power tour stuff.
Still looking at building a budget 302 TT TPI. I have been pondering the following threads.

1) Siamesed runners and intake.
https://www.thirdgen.org/techbb2/sho...threadid=96858

https://www.thirdgen.org/techbb2/sho...siamese+intake

2) Ported stock L98 heads per..
https://www.thirdgen.org/techbb2/sho...ng+stock+heads


add low comp forged pistons, Hot Cam, 4.3L LT1 crank, rods and I have two SAAB 900 turbos with .48 a/r and two matching intercoolers. any thoughts?

EDIT- Doing some quick math shows the 4.3 crank (3.00" stroke) and rods (5.940") will allow any 350 SBC piston (1.560 pin) for a zero deck height(on paper). Also the rod/stroke ratio jumps from 1.63 to 1.98. Now I know that building a 355 would be a bit cheaper plus the added cubes, but I like to be a bit different. The grin factor alone for building it is enuf for me to give it a shot. Any ideas of power at 15 pounds? I should think 450 - 500 HP shouldn't be to hard to acheive with some tuning. cheers, Bob

 

Hey Bob, if you're really looking into doing the twin turbo 302 I'd go over to the junkyard turbo group on yahoo. A couple of months ago there was a really good discussion over the benefits/ disadvantages of the destroking. The general consensus was that using a 350 is better than the 302. HTH's.

 

Thanks Greasemonkey, I'll look into that thread. I realise that the 355 would have more overall power and torque but again this is something I may do for grins just to be different than 355/383/406 all of which in the end really have more power for not much more cost and would have 450 - 500 ponies without the turbos. thanks. Bob

 

yeah I forgot steves was a LS1, but the GM proving grounds car that mark built (came out in like 96 or 97 maybe) used that 4.3 v8 1 pc rear main seal stuff you talked about. some of those 4.3 V8 rods are even PM rods! I didnt realize you wer goind 302 TPI, it always seemed to be a bad idea without a power adder (not that my 283 was ever a great idea either) but I like the SAAB turbo deal. I was thinking maybe a couple of these little babys on the 283?

 

I wonder how high you'd have to rev a 283 to get that thing to spool. :sillylol:

 

LOL-I wonder how many 283's it would take to spool that thing, could come in handy at the tractor pulls without needing all those expensive blowers, of course telling people you make like 600 hp but that it is with 4 small engines just doesnt quite have the zip

 

My Lord....pets and small children beware... :hail:

hehe, lets see take two 283's join the cranks and build one of the largest Tri- Y headers ever seen......


Do you think the SAAB T3's with a .48 will work? Everything I have found says that they will support 150 CI max each. Would the T-bird units at .63 be a better choice? What I am looking to do is build for no more than 6K RPM and around 500 horse for a street toy, so MAX everything isn't my goal. thanks, Bob

 

I'd probably go with the .60/.63 T-bird units. They've taken guys into the nines so I don't think they'll have any problem doing what you want. I know some of the guys on the junkyard turbo list have had good luck with the .60/.43 (i think) units on their 302's, but I'm not sure on how high they were revving.