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Full boost in 1st with t3/t4?


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My question is who out there can get full boost in 1st gear with a larger than stock turbo? Im running a t3/t4 with a 50 trim and a stage 3 exhaust housing and i can only get around 7-8psi in first gear, the tires are not spinning. Im running megasquirt and i think it might be a tuning issue because it seems really laggy. This cant be normal can it?

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im running an external tial 38mm, it was expensive enough it better not be leaking.... but i have read about finding some way to pressure the the atmosphere side of it with 4 or 5 psi to help it stay shut untill it gets to the 12 i have it set at now. thing is im not sure how to go about regulating the atmosphere side to only 4 or 5 psi

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Cygnusx,

I am running the stock 3.54 turbo gears with the nissan tranny, but 1st is pretty slow im definately not blazing through it smoking the tires the whole way. 2nd gear ill get full boost but its pretty late, around 4000 and third is a monster pulling hard all the way from 3000 to readline.

240zturbo,

Are you asking if i have one (electonic wastegate controller) or if thats what i would hook up to the atmosphere port on the wastegate.....no i dont have one but that is one way i could apply pressure to the atmosphere side of my wastegate, i just dont really want to spend a lot more money on it right now. The t3/t4, Tial, megasquirt, injectors, IC, and TB kinda broke the bank.

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Now that im thinking about it, i think it used to boost a lot better in first before i installed my blow off vavle, its a cheapie... ive been doing so much to my car lately so its kind of hard to remember how it ran before/after the blow off valve. Im going to tighten that up and see what happens. Ive been searching about blow off vavles leaking, and it seems like it is a fairly common problem...

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my T3 boosts exactly as mentioned as well..........not much(3-4 psi) boost in first,no wheelspin,reaching for second quickly............about 10-12psi in second by 3500rpm,starting to wind up nicely.............pulling hard in the top 3 gears,15 psi by 2000rpm

this is on an RB30ET in a 240z,3.36:1 diff ratio

i often think first gear is a waste of time as the ratios are to suit the donor vehicle which was 500kg heavier.............so i'm going auto and probably bigger BB turbo(GT30R)

my research leads me to suspect that the old school turbos are no match for newer technology............going to put my money where my mouth is real soon,lol

paul

WA

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My T04B-h3 with a T3 stage III turbine with a stage 1 MSA turbo cam will get full boost (12 to 14 psi) by 3500 rpm in all 5 gears using a 3.90 diff.

 

I found that low ignition timing and/or a rich mixture will slow down the boost application in first and second gear.

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  • 1 month later...
I can. If you are too rich it will add alot of lag. I like mid 12's even low 13's don't bother me till the boost gets up there, then a little richer. Not enough timing will also do the same.

 

Clifton, Just curious, how much timing do you run at say 10, 15 and 20psi? Right now I'm running 29 at 10psi, 26 at 15psi and 24 at 20psi. I've seen as much as 3 or 4 degrees more timing is some other folks setup.

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I was looking at my video again and it seems like I'm hitting 12 pounds in 1st, then 13-14 in 2nd with the stock T3 but I never get wheel spin, unless I'm on slick blacktop. It pulls pretty good. Ask the guy in the 06 GTO I pulled from at a light:wink: could be better if I had Megasquirt? I think I'm running rich......I have alot of black soot in the tail pipe.

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Clifton, Just curious, how much timing do you run at say 10, 15 and 20psi? Right now I'm running 29 at 10psi, 26 at 15psi and 24 at 20psi. I've seen as much as 3 or 4 degrees more timing is some other folks setup.

 

On my L28 I'm running 22* total at 22 psi. I only run race gas with it though. On my 7M I'm at 19* at 23psi. I'm going to pull it back to 17* though. I just got the MSII going on it 2 days ago and am in the middle of getting the afr's and timing perfect. I just did a datalog last night and found it was a few degress higher than I want. I'll post the second one so you can see it though.

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I have an '83 ZXT with 3" echaust from the stocfk downpipe back and a T3/T4 - S3 trim .70 AR on tghe cold side and a clipped turbine in the stock housing on the hot.

 

I get full boost in 1st - as a matter of fact, the boost comes on so hard and fast that the engine shuts down unless I leave a little bit of throttle pedal left to feather in as the rpms go up - no pedal to the metal with this setup (this is a 1st and 2nd gear only phenomenon, and the main reason I will be going to MegaSquirt in the near future - Aug. is the last time this car needs emissions testing here in the Atlanta, GA area).

 

I can't wait to get bigger injectors, crank fired ignition and an intercooler on this puppy....

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