I'm looking all over for a cheap motor to start mocking up my GT turbo mainfolds and DP's on and I just realized that I have 2 2.8's sitting at the shop. Anyone know if the blocks are identical to ours dimension wise? Much cheaper than buying an S motor just to sit around.

 

Yup, if you have the heads, I would pull them off, & swap'em on the 2.7tt! The 2.8 heads are almost the RS4 heads.

 

I found an older thread that someone asked if the 2.7 exhaust manifold would bolt up to there 2.8. One guy said NO! and that was end of thread. 2ks4, you say they are almost the same as rs4, so that must mean that the exhaust port layout is the same. So that must mean that the manifolds would bolt up to a 2.8 unless there is something else in the way. So that guy in that thread must have been wrong. 2ks4 are the ports much bigger on the 2.8? And is the combustion chamber the same amount of cc's? Just curious cause rs4 heads are practically impossible to find.

 

Humm, I'm not 100% sure, but I do know 100% that the 2.8l heads flow more & are said to be very close to the RS4 ones.
I do know 100% that the 2.8l heads are bolt on for the 2.7t, so the manifolds should then bolt right up.

They are a real upgrade for the 2.7t.

 

From what I heard the 2.7 and 2.8 are identical, when they went to turbos they just bored the cylinders less to thicken them up for the extra abuse. So if that was true then they would be identical for matching parts. And I never thought about that with the 2.8 heads that would be a sizeable upgrade especially if you ahd a little work done to them.

 

This frustrates me, I did some searching and never really stumbled upon this earlier. When I had to pull my heads to replace some extremely expensive valves and then spent alot of time porting and polishing them I could have found some used 2.8 heads with good valves and I would have saved me some time and been better off. I wonder if the intake manifold is the same but of course the enlarged intake ports cause our intakes don't have much material to enlarge it very much to possibly match the 2.8 head.

 

The blocks are very different, the 2.8 is alm alloy. The intake mani is very different, the 2.8l TB is in the back, VS the front on the 2.7. The runners are also very different.

 

Yeah that does make sense. Although I would think that with a forced induction engine having a constant above atmospheric pressure might not affect the whole pushing intake charge out of cylinder as much as an engine that is pulling a vacuum and trying to get a near perfect atmoshperic pressure inside cylinder. I just port matched and cleaned up the intakes and polished the exhaust ports and exhaust manifolds and polished the combustion chamber. I really didn't remove much material. Although going to a rs4 head with the bigger runners gains more power so I think forced induction is a whole different story. Maybe not. [&:]

 

I was thinking the same thing. A N/A car draws in all its air from the suction of the piston moving down but if I don't know if the smaller ports would help with FI. Also to me it seems suprising that if the power if better across the whole powerband why the vehicle doesn't come like that from the factory. Car companies do a fair amount of R&D and they have some methodology of coming up with the stock part so I am a bit skeptical about this applying to all vehicles.

 

Exactly

I think if u use the 2.8 heads on a stock 2.7T u will lose torque down low and u mite end up with betta flow up top - in other words u will lose thereponsiveness of the motor?

The 2.8 heads are designd for the atmo, were as the 2.7T heads may have smaller capacity and smaller portsbut are sized so coz they need to be a bit more narrow so the intake air comes in at speed& exhaust gases hit the turbine (hot end of turbo) very quickly - thus giving u very good response

If u after all out power the 2.8 heads may be a good cheap alternative, but if u after a good responsive motor stick with the 2.7T heads