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Discussion Starter · #1 ·
I have a 83ZXT with 168,000 miles on stock engine. I bought it for $300 (whole car). Spent $1200 on T04, intercooler, boost controler, fuel pump, as everybody on this page told me to do. Running 15-16psi I took it to the track it did a 13.5 @106 on street tires 205/60/15, burning them all though 2nd gear! I had it dynoed today it put 340ft/[email protected] and [email protected] to the ground (at rear wheels) This = about 410ft/lbs and 320hp at the crank!!!!. Here is my problem, my hp dives after 4600-4800. I want to change this over to MASS AIRFLOW SENSOR. I think it's the problem, I know somebody knows how to do this,please help. I already have the sensor, in fact I have a whole 84 300ZX.
 

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Re: Help with airflow meter &turbo guys check

> Hey Tony do you have a boost dependent fuel pressure regulator. Some people call them FMU's. Anyway, without one of these you will be running lean at the top of the gears. Bell engineering sells them for about $150.00. I have a similar set up on my Z and it runs [email protected] on street tires. I still have the stock airflow meter and all my fuel injection is stock as well. Let me know if you have the regulator I was talking about. If you don't you need it. if you do then you just need to tune in the proper fuel pressure. Good luck.

I have a 83ZXT with 168,000 miles on stock
> engine. I bought it for $300 (whole car).
> Spent $1200 on T04, intercooler, boost
> controler, fuel pump, as everybody on this
> page told me to do. Running 15-16psi I took
> it to the track it did a 13.5 @106 on street
> tires 205/60/15, burning them all though 2nd
> gear! I had it dynoed today it put
> 340ft/[email protected] and [email protected] to the ground
> (at rear wheels) This = about 410ft/lbs and
> 320hp at the crank!!!!. Here is my problem,
> my hp dives after 4600-4800. I want to
> change this over to MASS AIRFLOW SENSOR. I
> think it's the problem, I know somebody
> knows how to do this,please help. I already
> have the sensor, in fact I have a whole 84
> 300ZX.
 

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cause

What is the size of your turbo, some specs please! Anyway, the cause of your power drop is not your AFM but your cam. Power peaks on a stock cam at 4800 rpm. It doesn't mean you can't get more power, just that your power band is limited with that cam. I bought a cam from Top-End Performance that pulls to 8500 rpm and is streetable. In going to this cam you will want to get a 3 mandrel bent downpip and some sort of free flow intake.
 

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Discussion Starter · #4 ·
Re: Help with airflow meter &turbo guys check

> I have a 83ZXT with 168,000 miles on stock
I do have a aftermarket fuel pressure regulator. I can adjust the base fuel pressure manually and then it increases with boost but I think It only increases at 1psi/psi boost
 

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Discussion Starter · #5 ·
Re: cause

> What is the size of your turbo, some specs
> please! Anyway, the cause of your power drop
> is not your AFM but your cam. Power peaks on
> a stock cam at 4800 rpm. It doesn't mean you
> can't get more power, just that your power
> band is limited with that cam. I bought a
> cam from Top-End Performance that pulls to
> 8500 rpm and is streetable. In going to this
> cam you will want to get a 3 mandrel
> bent downpip and some sort of free flow
> intake.
My turbo is a hybrid T04 60-1 rotomaster compressor and a stock T-3 exhaust turbine with high flow wheels
 

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Discussion Starter · #6 ·
Re: Help with airflow meter &turbo guys check

I haven't done this mass air sensor conversion. Jim wolf does it. It needs to be out of the 300ZX TURBOS. They have a much bigger air mass sensor, and the computers are different as well. You cannot use the stock 280ZXT computer. It needs to be out of a 300ZXT.
Later,
Tim Deesen

> I have a 83ZXT with 168,000 miles on stock
> engine. I bought it for $300 (whole car).
> Spent $1200 on T04, intercooler, boost
> controler, fuel pump, as everybody on this
> page told me to do. Running 15-16psi I took
> it to the track it did a 13.5 @106 on street
> tires 205/60/15, burning them all though 2nd
> gear! I had it dynoed today it put
> 340ft/[email protected] and [email protected] to the ground
> (at rear wheels) This = about 410ft/lbs and
> 320hp at the crank!!!!. Here is my problem,
> my hp dives after 4600-4800. I want to
> change this over to MASS AIRFLOW SENSOR. I
> think it's the problem, I know somebody
> knows how to do this,please help. I already
> have the sensor, in fact I have a whole 84
> 300ZX.
 

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Discussion Starter · #7 ·
Re: cause

> My turbo is a hybrid T04 60-1 rotomaster
> compressor and a stock T-3 exhaust turbine
> with high flow wheels

Your cam is not directly your problem. You can easily make (with the right mods) well past 300hp @ wheels to 5.5 to 6k rpm with stock cam (been there, done that).

Sounds like its constipated.
Need to know more about your setup:
-what kind of I/C
-what size I/C lines
-what size exhaust and downpipe
-what timing (ign)
-what kind of fuel pump - is it maintaining pressure to redline
-plug gap
-type of dyno and what the graph looks like (smooth, jagged, loopy???...)
-what is cam timing set at
-more exact turbo info -- what is the turbine wheel -- stg I, stg II or stg III.

If your are running a stage I wheel, then that is your problem. The stg I wheel will give you good response, but will cause HP and torque to go in the shitter past 4.5K.

See if you can post your dyno runs, it will tell me a LOT (sorry, I don't have a direct e-mail at this time)

Rcr X
'77 280Z-T 240hp @ wheels on dynojet @ 5,600rpm at 12 psi with upgraded T3 and totally stock n/a motor (w/NOS off).

BTW 240z turbo, you might want to research Datsun L6 series crankshaft harmonics before venturing to 8.4K rpm.
 

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You need 4-6 PSI per lb of boost

>What type of FMU do you have? You have enough fuel for 11PSI but need an addition 4-6PSI per lb above that.

I do have a aftermarket fuel pressure
> regulator. I can adjust the base fuel
> pressure manually and then it increases with
> boost but I think It only increases at
> 1psi/psi boost
 
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