I have a 91 N/A that seems to have roasted the apex seals. I have two more events this year and no time or money for a rebuild on the s5. I put a s4 out of a wrecked 88 in to finish the year. The problem is that while putting the s4 in I removed all emissions garbage, and gasket matched all intake ports (from the s5). Now I have what seems like slow throttle response and a general lack of power. I have removed the 5 and 6 ports, but they were gone on the s5 already. My question is does the s4 just have a lot less power, or is there something I am missing? I think I have checked and double checked all that I can. - and throttle response is non existant until the car is completly to operating temp. Any help or suggestions would be helpful.

 

from what i read in the FAQ the s5 had more hp than the s4

 

S4 non turbo engines are about 15 HP less, but only about 2ft/lbs less, so there should be little if any noticeable differnce in HP, if installed properly.

I'd be double checking the simple things like timing and vac leaks...

Also the S4 really needs the Aux ports to make decent torque under 3500 RPM. Removing them all together simply further robs you of any low end power (something that the S4 13B is much better than the S5 motor on).

 

They are two different series engines.

The S4 engine has less Horsepower, and you have all s5 components, computer etc. Electrics in the S5 are different than electrics in the S4. It's not going to run prefectly.
I'd just tolerate it, then put the s5 engine back in.

 

Thanks for your input, I have no experiance with the s4 - and wanted to know if there was anything I could have missed. I have checked for vac leaks - wiring problems - poor grounds and anything else i could think of. I may put the Aux ports back in with the electric pump and see if that helps. I may just deal with it until I can rebuild the s5.

 

The other thing I would be looking at is the intake runners.

Have you port matched the intake runners yet... the S5 intake on a S4 block typically makes less power than the S4 intake [on a S4 motor]; unless you port match the S5 intake runners and use a S4 LIM.

 

Huh?

Well... my s4 block in my s5 runs perfect...
As long as you put the S5 MOP in... it'll be fine. Just remember your new 7K redline. I don't think the Vac rack will bolt onto the S4 block, but I put the S4 rats nest in for now anyways.

The S4 block will make ALMOST as much HP with the full S5 intake as the actual S5 engine would... with all the torque (if not a little more with the heavier rotors).