90RS305

Couldn't have said it better myself!
Yes, that is one of my favorite things about the TBI cars here on TGO! I've seen stock time run anywhere from 17.0 to low 15's (me! woohoo!) Its fun watching all the different members go from thier first post "New here, what should I get for my car?" to "Couldn't dyno my car due to dyno not keeping up with torque" (ok, yeah, not really, nice thought though huh? ) Even though I haven't quite found the culprit yet, my car took a dump on me and in my attemps to fix it I completely dissasemlbled the TB. I really am no mechanic, never have taken one apart before, but it was SOO simple I could have fooled a few people into thinking so. Re-assembled it in a matter of minutes and had it back on the car. I LOVE these cars!!!

Bruce (90RS305)

Kat

iTrader: (4)

I agree totally. Once I get the 24 lb injectors and the 3.42s in it I should start turning decent times outta it.

BTW I only paid 30 bucks for the roller bumb stick

Kat

Grumpy

Of all the cars I've owned the 84 Firebird that I converted to TBI, and the GN are my favorites.

When I was running the Bird in late 92 is was just soo much fun to blow off the the 4th geners. While the mid 13s it ran were fair, it was on the open road where it shined.
I still get notions of putting together a real stealth TBI F Bod, just to see what one could do with all the new tricks.

83 Crossfire TA

iTrader: (2)

Was the firebird TBI or Crossfire? (I know, same thing but people seem to differentiate quite a bit between them)

FWIW, about the same time I was tinkering with my ’83 Crossfire injected TA, which was tickling the high 13’s and was also, easily the most fun car that I’ve ever owned. When I finally had to part it out I saved as many pieces of it as I could and hope to build a better version of that car someday…

Dewey316

you should pick one up Grumpy, the TBI cars are dirt cheap.

JPrevost

I get the craziest looks when people ask me what's under the hood and I tell them a truck engine with mild bump stick and TBI.
I love my car because it's something I've put together and it's cost me virtually nothing vs a new car. Besides, what's so fun about a new car when you're worried about parking it next to a junker or you have no way of tuning something out of the original calibration! I can't stand how slow new cars rev down. That drives me NUTS. The only reason I would buy a newer car is for the brakes.... I'd rather have scrub brakes if it were an option.
I have a feeling that a dual TBI 350 with some trickflow or AFR heads and an Lt4 hot cam would do wonders at the track and still get unbelievable mileage with daily driver written all over it.

Grumpy

If it wasn't for my back, I wouldn't have let the first one go.

But, I've been thinking about doing a serious TBI. *Just* a 2 barrel.

va454ss

iTrader: (1)

You can just take over mine, when I install the solid roller

JPrevost

When you do that, also test out the BIGGEST spacer you can fit under the TBI. A general performance plenum volume is around 1.5*displacement, that's with port injection. So if you could get 10 Liters of plenum volume then you'll make more power than the dinky little intakes. Most carb/TBI intakes are made with small volumes to keep the fuel from falling out of suspension. I have a feeling that the reason why some crossfire intakes do so well is there plenum volume.
I'm a firm believer in big plenum for performance, small for emissions and gas milage but come on... you've got 7.4L of gas burning fury, gas milage is an after thought

va454ss

iTrader: (1)

People ask about my mileage. My reply is "I've never checked it".

I currently have a single plane with the Holley adapter and a 1" TB spacer under the TB.

It may have a little more than 7.4 liters when the cam goes in anyway, just to make things a little more interesting. The cam will be blower/nitrous friendly, so it may not be too bad to tune (I hope)

83 Crossfire TA

iTrader: (2)

Have you measured the plenum volume of a crossfire intake? It’s roughly 4.3L (including runners), too small to be helping much. The reason that spacers and similar stuff helps crossfire setups (and TBI setups in general) is that it increases the distance that the air/fuel can go before it needs to change directions. I suspect that if you got your plenum volume around 7-8L or so you’d see some advantaged from the large plenum also.

JPrevost

Have you measured a standard carb or TBI intake? 4.3L is HUGE. It helps more than I think you're giving it credit.
How does increasing the distance before it has to change direction increase power or throttle response?
It's resonance tuning and giving more even air distribution to all cylinders. There is a post about this on the DIY board. By having a large plenum the average air speed is decreased resulting in better/even plenum filling for runners that are close to each other physically and in firing order.
The resonance tuning of a large plenum is it's expansion rate. Going into a large area expansion (runner to plenum) there is a pressure pulse generated, the larger the expansion cross-sectional area the strong the pulse wave.
The trade off is that you don't want to have a super wide area expansion and have no height to the plenum because airflow will suffer. It's all compromise so by having ~1.5x the engine displacement you're on the verge of decreased throttle responce but maximum power. To think about it in terms of throttle responce you open the throttle (neglect fuel transmit time) and it takes less than 2 engine rotations to increase it's acceleration. 2 rotations is only 0.06 seconds so truethfully large plenums don't = bad throttle responce unless the tune is bad or you're still wet flow.