TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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Hello All,
I have a much used 89 RS with a tired 305 and TBI. I have long (20+ years)
lusted after a 302 crossram SBC. I was wondering two things, has anyone toyed with running 2 TBI's on the GMP cross ram manifold ? and what kind of room would have to be made under the hood of a third gen to get such a thing under the hood? I suppose I need the help of the real ECM guru's to determine how to run 4 injectors and what ECM I would need. RROB? your EBL be up to it? Please keep in mind that I am pretty well versed in Small blocks and understand that a 4"bore x 3" stroke is not exactly commonplace on the streets nor will it be a nicely streetable piece. lets keep the discussion to how to make it work, and not the Why would you do that thing, suffice it to say because it is what I want. Lets assume that I want this to be not race only but am willing to put up with a peaky motor that has to be rowed pretty agressively through the gears and can be driven on the streets (5 or 6 speed) A street car with a road race flavor if you will, I am not looking for a maximum effort drag motor. Also in the crossfire aplications... was there two of everything? IE: TPS and IAC ? how would be easiest to deal with this ? a progressive setup with one TB acting as a secondary or does the X ram plenum preclude this ?
I know ... a lot of questions but it is something I would very much like to do.
2 single barrel TB units(aka crossfire) or two - 2 barrel TBI units(aka 5.0-7.4L TBI)?
progressive linkage as holley does on the 4 barrel TBI unit would seem to be critical if you will flow 800-1000 cfms. would be a tuning nightmare as in low rpms the fuel mix will fall out of atomization once the fuel charge hits a cold manifold. not sure which ECU will drive 4 injectors and then sequentially(2+2) at that. seems a project for the "experienced" among us.
I was thinking more along the lines of 2 two barrel setups, and I dont believe the cross ram such as the "old" original z28's had would actually allow a progressive setup. I am sure the cold manifold dropout problem could be overcome with carefull tuning. Granted the mixure velocity would be lower to some extent, but these are/were geared more for the high R side of the house anyway. I think I am getting ahead of myself here as the manifold I was planning on using does not apear to be made anyway. I thought Chevy was still maing them, but on closer inspection they are making a cross ram but only for the 90 degree V-6's. I suppose I could use an offy but I was hoping for a chevy part.
I've thought about this to the point that I bought one off ebay a couple years back. Nothing done yet, just a manifold, a 327, and dreams. I imagine a new top plate would have to be machined to accept the twin deuce's. I was planning on running two 350 tb's and 4, 2.8L injectors (2.8+2.8 =5.6). Now that I think about it, 2.8 tb's would probably suffice for street use and provide better tip in response, not to mention better mixing of air & fuel. If the injectors were wired in series, sets of two, wouldn't the resistance be lower than the lowest, possibly frying the stock driver? So that leaves parallel. Would this be too much resistance for the stock ecu? Guru's? I'm thinking parallel would be best.....
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Oh yeah, I forgot... When it is on the block, sits no higher than centerbolt valve covers. Probably clear the stock hood. Custom air cleaner or 2 tiny ones. If tb's remain in stock location, center to center is like 9 inches or so. Not much room for air cleaner choice...
Last edited by 327; 05-19-2006 at 02:16 PM.
Reason: Automerged Doublepost
kind of like the crossfire injection on the 82 camaro and vette had too in like 81 and 82 used to be called "ceasefire injection" cause of all the problems they had with the system back in the days i think there are some people who run pretty good on thes setups but not sure
__________________ George
89 RS T-top, 305 TBI converted to TPI, flowtech headers and y- pipe, flowmaster cat back with 80 series muffler, tpis zz-9 cam, accel coil and wires, "camaro" grill, clear side markers, jamex STB, modified MAF and air filter boxes, K&N airfilters, reverse glow gauges, custom light up rear valance, edelbrock torque arm
I have a 84 crossfire set up on a Edelbrock Smokey Yunick 1 (SY1) intake on top of a 383. I am not an expert tuner but the cold manifold is not an issue. Once the engine warms up every thing is fine. This car is driven daily with out issue.
Offy still makes a cross ram intake for the v8 and the SY1 show up on ebay quite often. The crossfire linkage would make the set up very easy and it can support 400 hp for that 302.
Grab yerself a copy of CarCraft July 2004 and Sep 2004. There's a 67 Camaro with two Holley 4bbl TBIs on an Offenhauser cross ram manifold. He used all Holley gear, except for the manifold and throttle linkage. The throttle linkage is by Enderle. Only one set of sensors is needed with the Holley Commander 950 computer. It's not progressive, but with the computer controls, this really isn't an issue. The 350 gets 400 HP, and the owner claims 15 mpg.
It's a sweet looking setup.
Tim sends
PS, the biggest reason the Chevy 302 was a no-lowend, 6000 rpm powerband start was due to the large-by-huge camshaft it came with. Ford has done quite well with the 3" stroke for street manners.
327.. Yes there is a resistance issue ( but RRob assures me that his EBL will drive them) but you got it backwards....ie: resistance in series ADDS resistance in parllel divides. (nit picking to be sure but true nonetheless)
357 I was not aware anyone had done that thank you for the referance, now I just need to start rounding up parts and figure how to make a ram air hood to get it under a 3rd gen hood. I still think this would be the ultimate homage to the 'ole z28 plus I think a high winding small block in front of a 6 speed would allow me to sound like I was racing lemans with out ever getting beyound 3rd gear ! hmmmm maybe this would be more comforatable in a "Trans AM" being as that was its original intention ( race series wise , not platform)
Grey,
You may be able to find the articles on the CC website. If I run across anything else I'll let you know. I too, have a soft spot for the DZ302. I've a friend in the Denver area with a near original 69 model. Sweet.
I had an entire message typed out, hit preview and the whole thing got wiped out which sucks as I already closed out the pages I was citing. Oh well let's try this again.
I have an article at the house involving the Inline setup from Turbo City posted in the last link but they moiunted it on the Offenhauser Tunnel Ram manifold. If anyone is interested in the article or just seeing what it looks like let me know and I will upload it.
There is a user at another board that got a duel TBI setup to run on the Offenhauser crossram manifold though. Here is what he had to say:
Quote:
I have a 1990 Camaro with a 302ci motor. I picked up the Offenhauser dual crossram intake along with two TBI to 4 bbl adapters. This is kinda my homage to Duntov. Working with Dual 850CFM TBI units. Problem right now is getting the linkage made. Olny going to use one of the throttle position sensors. Just hoping that I dont have to screw with the wiring to bad when I split the injector signals......
Also for better O2 readings I upgraded to a 4 wire......
Quote:
Went with a MegaSquirt computer for the fuel system and ended up running twin 454 TBI's. Still working on the performance, but it started up on the first try. The offenhauser intake looks great on my third gen.....
You might want to contact the user rocket-doc there and see if he can aid you on this issue. I know he didn't use the Holley 4bbl versions but he did have to play with the wiring, linkage, and the programming.
That's all I came across after quite a few web searches. BTW, speaking of old articles there is one from 1999 I need if any of you can direct me to it. It's Part 1 of "Project Silver Streak" SuperChevy built and gave away. I bring it up since magazine archives were mentioned.
btw, I too, have always wanted to beat a 302 in my own car. Here's an easy way. The newer (93-94?) caprice was offered with a 4.3L LT1. Did some research and it has a 3" stroke. One piece rear main and large journals. The possibilities are endless as to what 302 you could build. Of course, you'd have to use the correct pistons. As long as custom pistons are in mind, run 6" rods. A chevy small block at 10,000 rpm, anyone? Anyone? Has anyone seen Ferris Bueler? You could even do an LT1 302. Any 350 block, 86 and newer, is fair game. With a turbo, this'd be one nusto setup.... Of course, it would have to have some sort of crossram..
Dang guys sorry to bring up such a dead post, but i was searching cross ram builds on google and found this.
i just took my small journal 327 block and steel 283 crank to the maching shop. I'm using off the shelf small journal scat SIX INCH 4340 rods 230 bucks. found a cheaper 6" 5140 for around $170. here's the really sweet part.
- 302 pistons are impossible to find & customs are pricey. although srp makes some #140053 that work ( 3 9/16 stroke 5.7 rod) I am using a set of new forged manleys i had "laying" around for a stock rod/stroke 350. (.030) these come out .035 ABOVE deck. mill .050 off the block and run a .080 titan head gasket for a near perfect .040 quench area. also awesome 2:1 rod to stroke ratio. And no pistons are cheaper than 350 pistons. Mine are flat top so i'll have to use some heads with 49cc chambers to get good (11:1) compression, but had i not had the pistons i would have just bought some domed ones.
I've been wanting to build this forever and kept looking for a sj 327. COMPLETLY forgot about the 4.3 lt1. i knew they made it and it would fit modern lt-1s but NEVER thought of running one in an 86 up block. Are you sure it would fit? and were they steel cranks?
I remember an article back in 96 where Chevy did just that. They took the 3" crank and 5.95" rods out of the 4.3 V8 and put them in a 350 block with stock 350 pistons. Topped it off with LT1 heads and intake along with the LT4 Hot Cam and backed it with a 6speed trans. Claimed it made 400hp with respectible street manners. This combo was put in a 96 Z-28. I can't remember if this article was in ChevyHiPerfomance or Hot Rod.
Steve
Last edited by steve8586iroc; 02-25-2007 at 11:29 PM.
Reason: listed wrong engine
I remember an article back in 96 where Chevy did just that. They took the 3" crank and 5.95" rods out of the 4.3 V8 and put them in a 350 block with stock 350 pistons. Topped it off with LT1 heads and intake along with the LT1 Hot Cam and backed it with a 6speed trans. Claimed it made 400hp with respectible street manners. This combo was put in a 96 Z-28. I can't remember if this article was in ChevyHiPerfomance or Hot Rod.
Steve
I've done just the opposite to a L99 Caprice that I wanted to get back on the road. Had a rod knocking 265 in it. I put a stock L03 rotating assembly in the block. Made a 305 LT1 in the process. The L99 shared the 305s 3.736" bore, but used a 3" stroke.
whered they get the 5.95 rods? is that stock lt1 or are they an odd aftermarket? and does anyone know if an lt1 crank will fit in a 86 up block? whats the difference?
Hello All,
I have a much used 89 RS with a tired 305 and TBI. I have long (20+ years)
lusted after a 302 crossram SBC. I was wondering two things, has anyone toyed with running 2 TBI's on the GMP cross ram manifold ? and what kind of room would have to be made under the hood of a third gen to get such a thing under the hood? I suppose I need the help of the real ECM guru's to determine how to run 4 injectors and what ECM I would need. RROB? your EBL be up to it? Please keep in mind that I am pretty well versed in Small blocks and understand that a 4"bore x 3" stroke is not exactly commonplace on the streets nor will it be a nicely streetable piece. lets keep the discussion to how to make it work, and not the Why would you do that thing, suffice it to say because it is what I want. Lets assume that I want this to be not race only but am willing to put up with a peaky motor that has to be rowed pretty agressively through the gears and can be driven on the streets (5 or 6 speed) A street car with a road race flavor if you will, I am not looking for a maximum effort drag motor. Also in the crossfire aplications... was there two of everything? IE: TPS and IAC ? how would be easiest to deal with this ? a progressive setup with one TB acting as a secondary or does the X ram plenum preclude this ?
I know ... a lot of questions but it is something I would very much like to do.
Thanks
Dan in Alaska
I know this is old and I don't even know if you are still on this website.
But here goes.
Of course, it would have to have some sort of crossram.. 
Are you sure it would fit? and were they steel cranks? 
Paul 
