Ok.. so one night i just had to go out and try high speed acceleration of my new rear.. i swaped in a 3.27 posi to replace the old 2.71..

I'm really happy of the results at lower speeds (0-60) but i seem to have a throttle problem... i started the test by going on a fairly good country road... when i got to about 50mph i pushed the peddal half way in a calm way (didn't want to spin the tires because of the icey road ) the car pulled nicely and strong to ~120mph in third gear at about 5000rpm.. i let of and i was very saticefied of the preformance.... i wanted another run so again from 50mph i pushed the peddal this time all the way down... i was dissapointed... the car didn't seem to pull any harder than at half thorttle... i tryed a few times but no diff between half and full thorttle... last summer i had a problem with the car lauching like and old lady while at wot.. the new posi did help from a stand still but why isn't there a difference between wot and half throttle?? i have a fairly stock and well tuned up engine and only 76k on it...

any help would be nice...

thanks in advance

 

The torque of a TBI just falls flat on its face after 2400 rpm. By 3800, you've got little to nothing left in that department due to the numerous restrictions of the TBI design, (heads, headers, y-pipe, intake, TBI etc...)

I did a swap to 3.23 gears around 6 years ago. It wasn't till I started some serious tuning and tweaking that I managed to get some pull out of it. She'll pull well up to 92 mph (3rd gear), after that its a struggle until she hits her peak at around 130 mph.

For me there's no fourth gear wot either, haven't installed the valve for it yet in my tranny. I do have ram air that really works which is why at 2/3 throttle it can and does pull to 4000 rpm in fourth for me.

In 2nd and 1st I can get it to redline 6000 rpm although it's no benefit to do such shifts as at 5300 its surging due to header restriction.

 

I don't have an answer to your question but would you answer me one? If you were scared of spinning your tires at 50 because of the icy road conditions then what were you think while you were doing 120?

Steve

 

well i'm out of my mind doing 120 on stud tires... but it's safer to drive 120mph not spinning the tires than doing 60mph and having the car do a 360 into a tree

I get a good rush from speed.. and i have learned to controll my lead foot the hard way

I haven't kill anyone... yet

Just kidding... i'm really not into risking myself or anybody else... usualy..

 

But why am i not getting any difference between wot and half thorttle???

 

At WOT despite the fact your giving opportunity to flow more air, the flow in the intake, heads and headers is not enough to take advantage of the increased capability to flow more air.

The heads in stock form have small passages as is and are swirl port I believe making high flow and high rpm fairly impossible.

The headers are logs that cause obstruction to the flow by their very design. The intake isn't big at all, full of coolant passages to keep things toasty in there for keeping the fuel in suspension.

So what people have said all along that the TBI itself is not a restriction to performance (300 HP capable by all intents and purposes), its just everything else its mated too isn't a performance item.

Also in stock there's a hell of a lot of casting flash at the areas the intake meet the heads and the exhaust to the headers. from the "mass production" of these cars. Just getting that crap out of the way helps performance too.

305 TBI cars respond well to mods because they are so restricted to begin with.

 

yeah... thats what i thought... well would you suggest to get an edelbrock preformer tbi intake?? i got a friend who know a guy that ports and machines cylidar heads and does valve jobs for racing apps. he's never done a v8 engine before and is very intrested in seeing the results. Hes done the heads for my friends "rally cross" car. they got 170hp out of a 1.6 liter 4 cylinder boxer engine with a carb.. can't wait what we're gonna get out of the lo3... headers i'm gonna get as soon as my budget lets my...

How much hp/Nm will the stock down stairs take??

I am gonna get 300hp off the crank by this summer.. even if it takes nos to do it

It's cheeper over here to mod rather than get a $2000 used pos tpi.. i'm not saying theres anything wrong with l98 lb9... but all the used engines over here are crap...