r90camarors

Just got done taking the camaro for a ride after doing some modding.....and all I can say I Holy $%^#!!!! Needless to say, I make a promise of mid 12's on street tires. Anyways, on to the TBI mods. Some could be considered the ultimate tbi mods, and I had done some previously, but anyways

1) Obvious rounding of bore inlets (previously done)
2) shaved the injector pod mount that over hangs the bores
3) rounded the edge of the blades, front and back. Didn't completely round it as I didn't want to go too far.
4) Shaved the throttle shaft
5) filed the screws holding the blades level to the throttle shaft
6) Narrowed the are cleaner mounts
7) Injector pod spacer (previously done)
8) Polish on the blades, bores, and injector pods (previously done, but redone, 2,000 grit)


More importantly however was the mod to my Holley squarebore adapter plate.
For those using it, you know that there is already an open gap between the intake divider plate and bores on the adapter. Basically opened it up like shown in the attached drawing. I also angled the bottom side out for what was left, and polished it as well.
I think the open adapter allows each cylinder to draw from each bore, thus furthing my opinion that single planes are actually the route to go for high reving/power making engines. Definetely no loss in low end torque with this mod either.
With my new Spec stage 3 clutch, this thing is a beast. Unfortuantly, I had to disconnect the ram air and do this with the open element, as the rpm airgap in conjunction with the ram air does it's job so well, that my tbi ices over. Only way I can think to over come the problem is to plumb a coolant line in the adapter plate, and bypass it when the weather warms up.

Anyways, hopefully i'll get some pictures soon, just need to talk my self into a digital camera.

BMmonteSS

Just out of curiostity how much fuel pressure are you running? I'm running a slightly milder setup than yours with 75 pph injectors.

rsilver

r90camaro, thanks for posting this. What does your sop dyno tell you about the improvements from this mod by itself?

This issue of TBI icing or running too cold is a big one. I have talked to several pro tuners (if there is such a thing) and all have said that the tbi needs heat to run properly and consistently.
That is my concern about the 4bbl set up and the heated spacer is i think about 1 inch tall. Not much room for stock hood clearance.

Do you know if a holley heated spacer can be opened up between the bores or is there water there also?

Great post . thanks..................bob

r90camarors

BMmonteSS,

I'm running 22.5 psi currently, which is as high as the stock holley spring will allow before bottoming out the regulator diaphram. I'm gonna make some aldl runs this afternoon, and let you know if I'm lean at WOT. I have a spring that should allow up to 26psi, just haven't installed it yet. I learned the hard way that doing multiple mods at once is a bad thing......It's just that much more you have to troubleshoot if something goes wrong.

rsilver,

Hell yeah there was a SOTP difference. I really think my engine combo is nice, but unfortuantly the 2bbl has choked it. So everytime I do something to supply more air, i.e. rpm airgap, ram air, tbi and adapter plate mods, I have felt nice gains.

I think the tbi running cold issue has two aspects, though I think you have the right idea. Just from my personal experiance: TBI icing over is a bad thing, though you still want the coolest mixture at the cylinder. I think that if you can keep the tbi temp above 50*, all is good.

Honestly, I am not too familiar with the Holley adapter you are talking about. I have seen it in the holley catalog. But the standard adapter plate I have is an inch tall as well.......but the down side (from a $$$ aspect) was that with the rpm airgap, there was no clearance and I needed a new hood.

I am thinking about adding the coolant passages myself in the one I have. It shouldn't be too hard, and is an option you can try if you want to open up your adapter as well.

va454ss

iTrader: (1)

Guys, I experienced icing of the throttle blades on a 50 degree day. I was also using the RPM Air Gap intake.

I recently switched over to a single plane and the results were phenomenal. No loss of low speed response and the increased airflow up top made my lean out even worse.

Anyway, the intake that I'm using is a single plane with EGR provison, and of course, no air gap. It actually is shorter in overal height than the RPM Air Gap. I drove on a 30 degree day and experienced no icing of the throttle blades. I didn't install the EGR valve but I used gaskets to allow exhaust to flow into the EGR passages in the intake. I also removed the lifter valley shield that I was using with the Air Gap.

My truck originally came with a spreadbore manifold and a water donut to adapt the TB to the intake. I used this donut to adapt the TB to the single plane I'm now using. My current intake has dual patterns on the carb mounting pad.

This factory donut may be something for others to consider. It can be used to circulate water to warm the TB if necessary, or used just to adapt the TB to the carb manifold. I know most performance manifolds are Holley square pattern, but maybe can be redrilled to also accept a spread bore pattern.

The only problem with the factory donut is that it is about 1" thick and may cause some hood clearance issues and man is it fugly! I dolled mine up a bit before installing. It also uses a single opening vs the dual bore setup like the Holley and other TBI adapters use.

Most people throw away these donuts; they may have a function after all!

r90camarors

Update:

I've been running the car (today will be the last day as snow is falling) and have fixed the icing problem as of two days ago. I removed the ram air for the time being and put the open element back on. I have not sealed the cowl openings, yet, but will if i decide to drive it and the temp is colder. My current IAT readings are right around 50 degrees at highway speeds, so the cowl is doing the job, but just warm enough to prevent icing.

Other major news......Like I said before, this thing pulls upper rpm like crazy, so crazy i hit the rpm limit in the chip around 6,400rpm. Kinda sucks, cause I think i could shift around 6,500rpm outta 1st and 6,400rpm outta 2nd at the track.....But the engine, being a stroker, is only built to rev to 6,500rpm anyways.

Though I do definetely agree with va454ss that a single plane can be very benificial and better than dual planes with tbi, I am starting to re-think swapping to one. Not so much that I wouldn't benifit, as I am sure I would pick up more hp. More so because of the whole red line thing and money issue (the downfall of vortec intakes).

In a cool side note, using winaldl log data, I went from 26mph to 63 mph in 2.4 seconds at 88% throttle (I still have throttle linkage problems after the intake swap......need to make a new bracket before WOT will work, and yes, tps is correct). I was going for a 0-60, but it's way to cold to get any kind of traction. Can't wait for spring

va454ss

iTrader: (1)

Amen!

Berlinetta

r90scamaro, are you having fuel delivery problems? You ever get to see if you were running lean at WOT? Thats one hell of a car you got there

Ronny

iTrader: (1)

R90. you commented you are using win aldl to determine A/F at WOT? do you have a wide band 02? how would aldl give you A/F at WOT ?

r90camarors

Thank you for the compliment

I don't have a WB O2 yet unfortuantly. All I have to go off of at WOT is the O2 readings in the log data. So it is a very vague look at my a/f ratio. I'm going to install the spring and bump the pressure up and see if my knock counts go down. I'll let you guys know how it turns out.

BadBlue91RS

What would stop you from grinding out/removing the divider between the 2 sides of the motor on a dual-plane intake? I would think that you would see great gains by making a performer RPM air gap, a single plane intake, wouldn't you?

r90camarors

The reason you can't grind away the divider plate is because there is a hieght difference between the two sides. I think rounding the divider plate is an option though.

Also, installed the spring, and was able to achieve 25psi before bottoming out the diaphram. Still a lot of knock. The problem has to be timing or poor fuel distribution.....the front two cylinders could be lean like va454ss's was doing.
But now it's super cold out, so more waiting unfortuantly.