eseloco

I've read alot here and, and came to the conclusion that with stock efi I cant go higher than 3-5psi boost. What causes this? does it hit fuel cut? or does the stock AFM flow too much and the vf signal can't keep up? if I upgraded injectors, went to forged pistons, and went to a tacoma style MAF couldnt I theoretically go up to 8 psi (my goal)

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abecedarian

The stock compression ratio is 9.0:1 on a 22re and the pistons are cast- not something you'd want to boost too high. Also, the ignition timing is controlled by the ECU and is not calibrated to account for turbocharging.
The 'fuel cut' is determined by the ECU based on throttle opening angle and air flow and is hit when the duty cycle of the injectors exceeds a certain amount. Adjusting the airflow meter (to compensate for larger injectors) can delay the fuel cut at the sacrifice of more precise fuel control at lower rpms but there is a hard cut at a certain rpm as well.
The 22re and 22rte use a VAFM (volume air-flow meter) not a MAF (mass air flow) and they are not interchangeable. VAFM/AFM are mechanical whereas a MAF is thermo-resistive (electrical) and the output different signals. It's theoretically possible to adapt a MAF to the 22re but as far as I know, the one kit that used to be able to do that has been taken out of production.

My investigation indicates that the 22re and 22rte use the same VAFM so it does not appear to be a limitation of the meter, but as mentioned, the design of the 22re (injector size, higher compression and the ecu programming) that limits the boost the 22re can have. Intercooling and retarding the distributor may get you to higher boost levels but you also will loose power from retarding the timing.

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Fofo

You have alot of options at your disposal.

check out http://www.22rte-trucks.com

You can find alot of useful info there

Also LC engineering has some vafm conversion kits but there spendy suckers.

eseloco

well i have a stock 89 22re. I recently purchased a 22rte manifold and ct20 turbo w/ downpipe. my plan was to rebuild my 170k mile motor with new forged pistons, with stock the stock compression ratio (around 9.0-9.3:1) and with a elec. boost controller limit boost to 6 psi on pump gas. 8 psi on race gas(101 octane from a local 76 staion)

my truck is a desert toy, full roll cage, fuel cell, c/o front suspension, and long travel national rear spring already done. intercooling is a must for the desert so that is no question in my case.

so to go over the 5psi limit i guess my only option is to either experiment with larger injectors, a a/f ratio gauge and the stock vafm, or go with the stand alone setup(megasquirt, sds etc.) im bascially looking for a way around the ecu limitations. but it seems that there isn't.

Sorry for the essay....ive had a little to drink, and its 3am where im at, and this is my second post.

HAPPY NEW YEAR YOTATECH!!!
-Jimi

abecedarian

HAPPY NEW YEAR!!!
and belated WELCOME TO YOTATECH!!!

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khoopes

Just lower the compression ratio and up the boost.

Factory is running 7.5 compression. I can run up to 14psi boost on my factory setup when I hit Fuel cut. The Turbo AFM is clocked differently to allow the induction stuff to hookup. It has a different part numer, maybe the guts are the same, but they are adjusted diferently I think. the ECM does not talk to the Turb AFM and repsond the same as to the EFI AFM. (I tried it when I did my conversion.) Keep in mind that for conntinuous boost above 7psi you need an intercooler due to temps... I know you already said you would do one. Do some searching and buy the turbo injectors, ECM and AFM, lower the compression... and have fun!

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400yzturbo

Sorry to jump in late in the conversation. I just wanted to put my two cents worth in on the 22ret. I rebuild a factory turbo engine for my toyota 4x4. In the conversion for my truck I got the turbo AFM, turbo ECM. I tried to put the truck stock and I had the same problem of hitting fuel cut before the turbo would really begin to create boost. I changed fuel injectors to 450cc. I was also running a T3/T4 hybrid turbo with a blow-off valve and on intercooler. The bigger injectors helped a lot. I could boost to a steady 20psi boost before hitting fuel cut, and sometimes I could even get to 25psi. I did encounter a problem though. The head bolts would stretch under high boost and it would cause my head gasket to fail. I went through 3 head gaskets in 500 miles. My two cents worth are: if you want high boost it would be a good idea to run ARP head studs or something equivalent to keep the head down. I should have done what I just mentioned, but after 3 head gaskets I was so sick of the turbo setup that i went to a V8. Good luck with the turbo setup.