Hi,

i know this seller is already talked about on this board but i've a question.
i want to buy from ebay the 590cfm tbi from Xtremefi/.
tbi

is this really e performance step further for me?
i have now a stcok tbi with the 65pph injectors but at higher rpm i think i've got too less air.
they say that i 'won't bore my edelbrock performer maniold out.
can this tbi really handle 340hp?
i think i've got around the 300hp now.

Thanks Tom

 

You can get a used big block throttle body for about 150 bucks on ebay right now, they have 2" thorttle bores supposedly flow around 700 cfm and you don't have to worry about crappy craftsmanship because it's a factory piece. Also you'll probably end up with the big injecotors (either 80 or 90 lbers).

I say your tune is more responsible for the flattening out than the TB. With your combo I would look into getting a bigge TB, but not before I worked on getting my tune perfect. If your datalogging you should see the map values starting to drop in the upper rpm ranges when your TB is too small. Anything more than 5 or 6 KPA is too much.

I'll make a wild guess and say your running out of fuel in the upper RPM range. I'm running 70 lb/ers and I have to run 20 psi + to feed my motor that makes ruffly 300 hp. JP runs 65 lbers at around 28 psi to feed his 330 hp crate engine. Both of these engines need lots of hands on tuning, and I say yours does too.

 

Hi,

i think my tune is not bad.
maybe you can take a look at?
i can't figure out the map values.
Tom

 

If you have any data logs I'd be more than willing to take a look.

 

i have 2 nice logs.

how can i show them to you?
thanks Tom

 

if they are .txt files, I think you can post them here directly. If you can't then just e-mail them to me at BMmonteSS@aol.com

 

over 15 years ago, hot rod magazine made 300 (crank) horsepower with an l03, a stock throttle body and 65# injectors. I think the stock throttle body moves enough air for a 305 in all but the most extreme applications. I agree with bmonte, it's surely the tune.

That said, however, I think there are benefits to having additional air if your cam and heads need it at higher rpms, and I disagree with Bmonte on the BB TB over the xtremeefi guys units. I own one. The workmanship is excellent and, because I sent him pics of my throttle body before buying, everything matches. it's a direct bolt on, which the big block throttle body is not.

Before you go worrying about swapping throttle bodies, however, I think it's critical that you get a handle on tuning. Every time you make a change, it requires different tuning. If you can't do that, you're just wasting your time.

 

With this issue ,it would seem to me that the thing
to measure is the vacuum, just behind the TB.

Has anybody ever done this?
Vacuum gauges, were once common.

 

it's just as easy to take a look at your map sensor if your datalogging, it's just an electronic vacume guage that reads in metric.

 

hi,
have you already looked at the logs?
i'm just curious

Tom