Engine wizards please chime in
#1
Engine wizards please chime in
A friend and I (both 93 GTS's) are considering the installation of 968 intake valves and S3 cams in our GTS's.
The questions of the day are:
1. Do the stock pistons need to be notched to accomadate the larger valves?
2. What about the increased lift and duration of the S3 cams? Will that force deeper notching even with stock valves?
3. If the pistons are notched will they need to be re-balanced?
4. If notching is necessary then we will also need new rods. Both engines have the weak, non-reusable 1-L rods. So this becomes a very slippery slope very quickly.
Any BTDT's out there please chime in! Your input is appreciated.
The questions of the day are:
1. Do the stock pistons need to be notched to accomadate the larger valves?
2. What about the increased lift and duration of the S3 cams? Will that force deeper notching even with stock valves?
3. If the pistons are notched will they need to be re-balanced?
4. If notching is necessary then we will also need new rods. Both engines have the weak, non-reusable 1-L rods. So this becomes a very slippery slope very quickly.
Any BTDT's out there please chime in! Your input is appreciated.
#3
Jim,
I am no expert here but think i can handle this one
No the pistons dont need any modifications, only the heads and their seats.
The S3 cams do need to be modified but i dont know specifically how, I do know they are apparently the same as GT cams but they are longer physically so must be cut down or something like that.
I know Roger was talking about replacing rods in his car which he will keep at 5.4L. I would replace those i guess. Please do tell, what rod manufacturer your using and what those were going to run.
And it was a pleasure to meet you at Sharktoberfest last month
Cheers
I am no expert here but think i can handle this one
No the pistons dont need any modifications, only the heads and their seats.
The S3 cams do need to be modified but i dont know specifically how, I do know they are apparently the same as GT cams but they are longer physically so must be cut down or something like that.
I know Roger was talking about replacing rods in his car which he will keep at 5.4L. I would replace those i guess. Please do tell, what rod manufacturer your using and what those were going to run.
And it was a pleasure to meet you at Sharktoberfest last month
Cheers
#5
2. What about the increased lift and duration of the S3 cams? Will that force deeper notching even with stock valves?
3. If the pistons are notched will they need to be re-balanced?
4. If notching is necessary then we will also need new rods. Both engines have the weak, non-reusable 1-L rods.
#6
I wonder what Sunset charges for the Set of 2R rods
I wouldn't be surprised it they were really damn cheap honestly, Of course they could be damn expensive too. Maybe someone should call and see before just assuming they would be like a billion dollars per rod cause zee come from zee factory
I wouldn't be surprised it they were really damn cheap honestly, Of course they could be damn expensive too. Maybe someone should call and see before just assuming they would be like a billion dollars per rod cause zee come from zee factory
#7
Kibort mentioned this a while back in an old thread about modifying S3 cams...
the mods, as was mentioned is $400 by elgin cams. one bearing surface is lengthened to fit the S4 heads. (exhaust cam on the driver side is the only change, plus the ends are cut off, due to no bearing surface at the firewall side needed in the S4 heads)
the mods, as was mentioned is $400 by elgin cams. one bearing surface is lengthened to fit the S4 heads. (exhaust cam on the driver side is the only change, plus the ends are cut off, due to no bearing surface at the firewall side needed in the S4 heads)
Trending Topics
#8
https://www.928gt.com/p-24047-92810300804.aspx
$175 x 8 = $1400. This gets right into custom rod $ territory. Add few $ and all of the sudden its stroker money. Just need crank, pistons and block and that it.
$175 x 8 = $1400. This gets right into custom rod $ territory. Add few $ and all of the sudden its stroker money. Just need crank, pistons and block and that it.
#9
https://www.928gt.com/p-24047-92810300804.aspx
$175 x 8 = $1400. This gets right into custom rod $ territory. Add few $ and all of the sudden its stroker money. Just need crank, pistons and block and that it.
$175 x 8 = $1400. This gets right into custom rod $ territory. Add few $ and all of the sudden its stroker money. Just need crank, pistons and block and that it.
I am going to call now that i have the PN
UPDATE: $131.10 per rod x 8 = $1050
Not to bad honestly, considering thats all that has to be replaced. sure custom rods are almost that price, but you spend a fortune on everything else. For a simple rod swap in the early GTS's, thats not too bad.
There are 850 plus rods available in Germany too
#12
#13
One of the front bearing surfaces on the S3 cams must be lengthened. All cams then must be cut off at the back (I guess you don't NEED to do it, but we do).
Even S3 cams with more lift than stock do not need deeper flycuts. But the width may need to change as mentioned.
Even S3 cams with more lift than stock do not need deeper flycuts. But the width may need to change as mentioned.
#15
In general GTS motors have incredibly mild cams.....and respond VERY well to GT cams..... Around 330+ whp with just the cams.....
With 85-86 cams modified to fit would be similar....of course having those reground by elgin would be a monster....maybe 400whp?