throttle body/injector size

[project60degree]

im currently building a 3100 and i was wondering if anyone has any ideas about TB and injector sizes i should go with. 97' cutty supreme

current/upcoming mods- .060 over, balance rotating ass.,milzy stage2 cam,gasket matched ported everything, forged pistons,roller cam/rockers,SS valves w/3angle valve job, block/head decked,adj FPR, venom fuel pump(90psi max),under drive pulleys,headers,2.5" exhaust, msd ignition box(dis +4), accel coils, dis interfaces, moroso blue max wires, ac delco iridium 41-101, gap ???, granetelli MAF, OBD II, SFI

[donk_316]

RE: throttle body/injector size

Id say use your stock stuff but bump the fuel pressure...nothing in your build would make me think you would need "bigger" injectors or TB. Pretty basic build there.

[project60degree]

y do u think ill just need stock stuff i could maybe under stand the stock TB but injectors? why do you say stock injectors? i was told by many of my auto tech teachers to use about a 30 lb and just pump up the psi on the rail....TB would prolly help though right?

[eliteweapons]

How much of a horsepower increase do you think you are going to get with these modifications?? I did a quick sim of with some basic mods you listed and with 10.5 to one ratio, a cam giving 480 lift at the valve with a 215 duration. Your max hp will be 215 hp at 5500 rpm. thats a quick run but I don't see the need to go up to 30 lb injectors there. If you add boost then you may have to.

[project60degree]

those dyno sims are b/s ive seen it for myself my teacher built a 468bb(stroked 454) on the dyno sim it said it only put out 490hp and he had dynoed it at 685rwhp we did it spec for spec off the paper work to the engine to the decimal

[project60degree]

also u cant get very in depth with those sims such as ignition type, plugs, wires,fuel pressure, injector size, intake plenums and whats done to them...if u cant get everything in the sime then its not 100%..im not tryin to be an a**hole but i know some1 that does that all the time any its irritating...sry

[bszopi]

Keep the stock injectors until you have the engine running and get the computer scanned. If the duty cycle on the injectors isn't exceeding 80%, then there is no reason to upgrade the injectors.

And is it really that hard to type out full words and sentences and use punctuation? Or do they not teach that in school anymore... I hate trying to explain practical knowledge to people who type like they are in 3rd grade. Just because this is an internet forum, doesn't mean the regular english language is exempt.

[geoffinbc]

Thats true it is more of an educated guess type software. But some of the good ones are very accurate. The good ones let you enter vast amounts of information. So if you have accurate info then the sim should be pretty accurate.

The sim I did myself of a Camaro motor gave me the same numbers as GM speced for the 3.4L. But then again there are so many real world variables that the software eithr uses a constant for, or or just ignores.

[donk_316]

Those "bs sims" assume that your fuel is dead on. so saying "also u cant get very in depth with those sims such as ignition type, plugs, wires,fuel pressure, injector size" has nothing to do with it. And "intake plenums and whats done with them " wont change enough to be totally innacurate.

Face it. Forged pistons and SS valves and "hi-perf" fuel pump dont add horsepower. Get a real cam. Bump the compression higher and force feed that bitch....then youll need #30 Injectors.

My 240hp 3.4L uses #17s....its called "TUNING"

[eliteweapons]

Well I am not saying they are perfect. I never said that at all. I use them to get a good approximation of hp to match the components closer that just guessing off the cuff that just adding boost to a 4 cylinder will give you 400 more hp for example. And besides when you get a good dyno sim for $350 not the $50 one you get better results and more in depth settings. When I finish my new motor I will let you know how close this is.

[SHOoff]

those dyno sims are b/s ive seen it for myself my teacher built a 468bb(stroked 454) on the dyno sim it said it only put out 490hp and he had dynoed it at 685rwhp we did it spec for spec off the paper work to the engine to the decimal

No... i'm thinkin he's right and you're engine buildup is b/s. You're not gonna get as much power as you obviously think from it. Do you think you're building a 468? Cuz you're not.

Obviously he's given a better estimate that you. Unless you're gonna start producing flow rates on the intake manifolds and the heads.

[eliteweapons]

As I said good sims ask you those kind of questions like the one I am using.

[SHOoff]

And I do believe that those sims come out fairly accurate when given the proper information, do they not?

[xonelith]

My 240hp 3.4L uses #17s....its called "TUNING"

I have Milzy's stage 2 cam as well, and I have almost maxed out my stock injectors on my 3400. I'm not even close to 240 at the wheels.

I'm not sure of the similarities between the 2 motors, but I'm at about 92% duty cycle at 6400 rpm and I'm not running rich (at least not there). If you're not revin' that high, then you should be ok.

I picked up a set of 98 GTP injectors for pretty cheap. In order to tune, I need to have some room to add fuel. That's why I bought bigger ones. I really don't know a whole lot, but makes sense to me.