SPOautos

hey guys I'm going to be running 1200 secondaries and a upgraded fuel pump (prob the Walbro from the RX7store)

What is the most boost that should be ran with this setup on 93 pump fuel???? Mods would include all the standard bolt ons with the stock seq twins, streetported motor w/Hurley seals, Power FC, upgraded inj and pump.

I just want to know a pretty safe boost limit.

Thanks,
STEPHEN

Tim Benton

iTrader: (1)

Stephen,

I'd go the usual 15 psi limit on the stock twins. I know some have run more and all, but when you raise the boost, your timing in those high boost areas become more critical.

Did the rebuild go fine without a problem?

Tim Benton

SPOautos

So far so good, I think I'll be up and running this weekend. Thanksgiving and all that slowed me down. I prob could have been done last weekend if it wasnt for that. I went ahead and used 2mm Hurley seals and streetported it so I'm ready for some HP. I sent my Power FC back to xs yesterday to have them retune for the streetport and 1200 secondaries.

I was going to see if xs could turn the boost up some. He said the most they will do for stock turbo setup without having the car there to check everything is 14psi. I guess if I want to run more its going to be up to me to tune it.

I think when I'm done I'm going to head for a dyno somewhere, maybe Tenn. Spyfish knows of a pretty good place close to him.

I'm wanting to find the limits of the seq sys.

Later,
STEPHEN

ZoomZoom

iTrader: (2)

Well here is the skinny. The stock twins themselves can run 17 psi but they wont last very long doing it all the time. Also the PFC has limits of 17.5 psi anyways. The problem here is the fuel. You mentioned the most boost on 93 octane. That would be 14 to 15 psi. So yes you can run more boost but not on pump gas safely.

95R2-89TII Ground Zero

15-16 psi, and I think that you'll be all right on pump gas. I run that on my FD and I have 1200 injectors on my car too, with a Cosmo 20B fuel pump.

Sidestick

iTrader: (1)

What would be the boost limit with stock injectors, but running an SX Fuel Press. Regulator? I have all the usual mods w/ PFS PMC. Just wondering the best compromise for power vs. reliability with the stockers.

FEARED7

I forgot to tell you that when I put your engine together I put all your side seal springs in backwards, put all your corner seals in backwards, and then put all the oil control ring springs in backwards. then I torqued all the tension bolts with an impact gun. The engine will smoke until its premature, 1k mile death!

B@BNR Supercars

FEARED7

just kidding

FEARED7

Well maybe if we install the motor backwards it'll be ok


As for the boost, I'm not going to run over 17psi. The type of fuel is not what limits the stock twins, its the amount of fuel and the turbo itself. There are pleanty of guys running 17+ psi on pump gas with big single turbos which is WAYYYY more air volume than 17psi on the stock twins. I was basically making sure that 1200 and most importantly the fuel pump would be up to the task. I wasnt very familiar with the pump. I've since talked to Jason and he has reassured me that this pump flow way more than what I need.

The only time you need to run race fuel with the stock twins is if you car isnt tuned for the boost. Upgraded ecus and piggy backs would probably fall into this category.

Anyway, thinks for the help guys!!!!!

I'll probably run about 16psi at the track and 14 on the street


Oh yea, Sidekick....the stock inj hit 100% duty cycle at about 14psi of boost. You have the regulator so that helps give a little margin for error but with the PMS I would run over about 13-14psi. Maybe 12.5-13 daily and if you really have to you would prob be alright turning it up to 14 for a 1/4 mile but thats it because you running at the edge at 14psi.

Later,
STEPHEN

ErnieT

iTrader: (2)

Stephen,
Since you bought my injectors, I guess I can tell you how much boost I ran with them...
When I was racing my car w/ race gas I ran 17psi on stock twins. With pump gas I wouldn't go above 13-14psi. Just too risky.

SPOautos

Ernie,

Was your car dyno tuned with the 1200's??? If so what kind of a/f did you tune for? I've got a xs map and I'm going to take it to the dyno to brush it up and make sure its safe. Hopefully everything is going to be good.

Later,
STEPHEN

ErnieT

iTrader: (2)

Yes, Dave @ KDR dynoed it to high 11's, low 12's A/F ratio.