Eta Reving to 7k??

[nick475]

So I picked up an 87 325e about 2 months ago. It has a gauge cluster from a b25 and it te engine is able to rev to 7000... I don't think this is very good for the engine so I'm trying to find a way to get the rev limiter at 5. Any ideas? Also, it's a stock ecu in the car if that makes a difference

[Mr. Tasty]

you must have swapped DME to be able to rev to 7k. Stop doing it unless you know you have an 885 head. You will break rocker arms.

[dashboardmonkey]

I bet it has a coding plug from a 4cyl.

[MR 325]

Trust me, it's not revving that high. It won't!

You've got a 4 cylinder tach or coding plug in there.

[nick475]

Yeah I mean I've hit 7k a couple times and it seemed alright. So you think it's just reading 7k, when really its only 5?

[e30trooper]

it could be a eta cluster ( eta coding chip ) with a b25 (7k) tack installed.

[E30SPDFRK]

Is it b25 swapped?

[nick475]

Nope. Bone stock B27 with the stock ecu. No chips or anything.

[1fastm50]

Post pics of the motor.

[nick475]

[jo3y]

So I picked up an 87 325e about 2 months ago. It has a gauge cluster from a b25 and it te engine is able to rev to 7000... I don't think this is very good for the engine so I'm trying to find a way to get the rev limiter at 5. Any ideas? Also, it's a stock ecu in the car if that makes a difference

Sounds like someone did a head swap and went the the extra mile and swapped in a proper tach.

My ETA goes to 7k... with an 885 head and an old 318 moto cluster

[nick475]

you dont know the previous owner lol. he had no where near enough intelligence to do something like that.

heres the head though.

[jlevie]

Sounds like someone did a head swap and went the the extra mile and swapped in a proper tach.

My ETA goes to 7k... with an 885 head and an old 318 moto cluster

While a head swap will allow the engine to go to a higher redline, to get there you also have to swap in the M20B25 AFM, throttle body, intake, injectors, engine harness, and DME.

If the cluster is set up for a four cylinder engine, a real engine speed of 4500 would indicate 6750 on the tachometer.

[nick475]

so in that case, the whole thing is just scaled differently?

[jlevie]

so in that case, the whole thing is just scaled differently?

Right! The tachometer is expecting a frequency from a 4 cylinder engine, but getting a higher frequency from the two additional cylinders of a 6 cylinder engine. So the tach will indicate high by a factor of 6/4.