Don Carter

As some of you know, I'm in the middle of a big engine swap project (TBF car) but there's an 86 for sale in town with bent valves, and I can't help but wonder if the 89 heads I have from the TBF engine would fit on the 86 motor. I'm thinking the exhaust is the same, but the intake may not match up right. I also have a complete 89 intake, so if converting to S4 intake would solve all the issues, might be doable. The 86 cams may be more desirable than the 89's, but not sure if they can be moved from the 86 heads to the 89's.

From what I have read, the 86 heads have studs and the 89 has bolts, so can the studs can be removed and bolts used? Would the 89 bolt threads be the same as the studs? Like I said, I REALLY don't need another project, but if I have all the parts to get the car going.... can't help but think about it.

James Bailey

The compression ratio is too high guy in Australia did it and it pinged way too much.... valve pocket a bit small. exhaust manifilds are 3 bolt vs two bolt not a big deal

soupcan

S3 cams won't swap without welding and the exhaust manifold are not interchangable.
The whole S4 topend is a bolt on but the electronic would be the hard part.

soupcan

If S3 and S4 exhaust can be swapped and people swap S3's to 4.7's can the S4's be used on a 4.7?

BC

If you can run e85 then you can do exactly as you wish to do with the higher compression combination.

You'll need an S4 intake.

Trip..

James Bailey

I did not say they could be swapped simply use the ones with the right bolt pattern. So no the S-4 will not fit the 16 valve heads only the two bolt 85/86 will but the down tubes triangular flages are too far forward and back to bolt to a stock cat or Y-pipe.

FBIII

The piston will need to be notched similar to the s4 pistons.

Vilhuer

After making extra large (all 4 are 40mm) and deep valve cuts to S3 pistons will give 10.6:1 or little higher CR. Automatic GTS has had such setup for past 6k miles without major problems but maps did need some adjustments with Sharktuner before knock sensors were happy.

Don Carter

Thanks for all the info. I didn't mention that I also have the S4 exhaust manifold and pistons. Sounds like the exhaust manifold may not be the right length to mate upwith the exhaust? Not sure I want to get into swapping pistons.

I didn't see any comments about the studs/bolts, but I'm thinking the studs could be replaced with bolts. There are definately some electrical issues with converting to S4 intake as well, so bottom line, big project!

dbenton996

I don't have the cash to do this for my current race car engine build, but I might hang onto this pair of S4 heads I have and do this in the future. I don't see why the higher CR can't be handled with some tuning. Of course, I would expect major running issues with the stock maps.

Benton

^ Me posting from dad's acct

mark kibort

the only reason that all 4 cuts are so deep, is that the pistons are universial for both sides of the engine. (for piston offset issues)

each piston cut would have to be slightly widened. but, as you have seen on the S3 piston, the cuts are almost non existant on the exhaust, vs intake. 1mm widening on the intake cuts would be a 5 min job on the entire engine.

BC

89 heads are thicker at the bolt bosses, so you would need the 89 bolts or longer head studs.

BC

You would need to check if the 89 pistons have the tolerance group that the other block.... Wait - I am confused. You have a complete 86 short block?