[blacked out gti]

85 hp GX vs. 102 hp RD
Why does one motor have more HP than the other? One came in the golf/jetta, the other in the GTi/GLi. Both have 1.8L. Same bore, same stroke. Both used CIS-e. Both are 9:1 compression ratio. Why does one motor have 17 HP more than the other? I have both motors. I have both in 1979 Rabbits. Same exhaust, same CIS injection. I dont feel a lot of difference.

 

[henryjames]

Re: 85 hp GX vs. 102 hp RD (blacked out gti)

rd has bigger valves and i belive thay have flat top pistons for highter comp

 

[Peter Tong]

Re: 85 hp GX vs. 102 hp RD (blacked out gti)

GX are 9:1 compression ratio... RD are around 10:1...
GX had smaller valve head, RD has larger valves...
GX used CIS-lambda, RD used CIS-E...
GX used Tci-h old style electronic ign., RD used knock box ignition...
GX can make alot more power - just swap a JH head onto it and boost it

regards,
Peter T.

 

[The_Hamster]

Re: 85 hp GX vs. 102 hp RD (Peter Tong)

both did not have single outlet, the RD had dual downpipe IIRC.
ALL the stuff we listed boosted the output 17hp. now imagine when people say their new muffler boosted 5-10?

 

[blacked out gti]

Re: 85 hp GX vs. 102 hp RD (The_Hamster)

Are you guys sure about the compression ratio? I found a web site that says both are 9:1. Is one a solid lifter, and the other a hydrolic lifter? What are the vlave sizes for each engine?

 

[The_Hamster]

Re: 85 hp GX vs. 102 hp RD (blacked out gti)

from bentley:

edit: both are hydraulic.


Modified by The_Hamster at 1:17 PM 9-13-2005

 

[blacked out gti]

Re: 85 hp GX vs. 102 hp RD (The_Hamster)

I read today in a bently that the GX is 8.5:1 and the RD is 10:1
I am suprised to hear the 1987 GTi motor was a hydro head.

 

[The_Hamster]

Re: 85 hp GX vs. 102 hp RD (blacked out gti)

all A2 motors except the early diesels are hydraulic lifter.
that is all 85+ golf and jetta's, except the 85-87 diesels.
yes gx is 8.5:1, MZ is 9:1, and RD is closer to 10:1, but not quite i believe.

 

[wclark]

Re: 85 hp GX vs. 102 hp RD (The_Hamster)

Quote, originally posted by The_Hamster »

both did not have single outlet, the RD had dual downpipe IIRC.

I have 2 RD engines, both from '86 GTI. Both had single outlet manifolds with a donut coupling to a single downpipe from the factory.

 

[MYTHOS]

The dual down seems to depend on where the GTi was produced.
But then again, with 5 golfs/GTis I had in the past it seems like nothing is certain.