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How much Power out of an FI e28

Discussion pertaining to positive pressure E28s.
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whatareyoulookingat
Posts: 148
Joined: Jan 25, 2007 3:42 PM

How much Power out of an FI e28

Post by whatareyoulookingat »

What kind of Hp increases given psi ranges can be seen on an '85 535i. Also, how much PSI are people running? What would be the max recommended without sacrificing too much reliability?
Boru
Posts: 1028
Joined: Jul 04, 2008 10:09 AM

Post by Boru »

We see approximately 12whp per pound of boost. There are a lot of factors to consider but that's a good "ball park" figure. I ran 15-20 psi boost on my 6er with a tired old engine (before FI) for 45K mile before donating it to the TCDCCDR (TCD Clinic for Compulsive Drag Racers).
whatareyoulookingat
Posts: 148
Joined: Jan 25, 2007 3:42 PM

Post by whatareyoulookingat »

That sounds about right. I was figuring on 100 horses at 8 lbs, so thats not bad. How was the reliability on 15-20 PSI, did you have any trouble with it? My engine has 120k on it, but runs strong so I don't have any hesitation as far as boosting it, I am just curious how far I can push the envelope before I start causing problems. I will probably only run 12 to 15. I have a friend that wants a warm '98 Camaro, and I still want to be able to beat him through the straights, not just the turns :)
bimmerboy
Posts: 390
Joined: Oct 18, 2006 7:06 PM
Location: United States

Post by bimmerboy »

120k is brand new dude. The reliabiltity of it all comes from how well the car is turbo'd, and how well the tune is. An efficient turbo and IC, and a good well made manifold as well as other turbo components will be just as reliable as stock for the most part.
whatareyoulookingat
Posts: 148
Joined: Jan 25, 2007 3:42 PM

Post by whatareyoulookingat »

What are the pistons made out of, are they forged? Also what levels of horsepower (boost aside) will I be able to see before conrods and piston rings start to give. I will putting a copper headgasket and ARP headstuds in to keep from blowing the top of the motor up, but I hear rumors that the bottom end will take upwards of 26 psi [but not for how long]. I am trying to find out realistic goals, and a parts list/idea of how much it will cost.
turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

Is there any particular reason youre set on a copper HG? Thats a bit of overkill, and it does come with some comprimise.
whatareyoulookingat
Posts: 148
Joined: Jan 25, 2007 3:42 PM

Post by whatareyoulookingat »

I heard they are the best in high boost applications, so if I am wrong please correct me, as I have never used them before.
turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

Thats pretty general info. I'm using a stock head gasket and bolts up to about 19 psi in my m20. They say the m30 holds up even better. I dont think you'd need to go any farther than head studs and an MLS gasket. They say those MLS gaskets are mightly tough.
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