When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
What about the 85 cams.... as i did... seems they had near the same power, maybe 10hp less.
btw........ i have the GT cams from the holbert engine... missing a few teeth though... anyone interested?
There's quite a few alternative approaches.
Almost any reasonable camshaft combination that you can dream up will startup and run in a 928.
How well they run is the mystery....and basically what this current discussion is about.
I've got two sets of cams, from two different supercharged engines, that I could not figure out what the cam grinder was doing or trying to do.
No idea of who ground them, but one set was removed from Andy's GTS supercharged engine (never ran well) that we built a naturally aspirated 6.5 liter engine for.
I sent them up to my friend, Dema Elgin (genius camshaft guy), and asked him to profile these cams and tell me what they were about.
He also has zero clue about what the goals were or how the engines could possibly perform with these cams. Supercharger, turbocharger, or naturally aspirated.....nothing remotely makes sense.
Scrap metal.
It happens!
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Did anybody program Mike Simard's cams? That would be pretty interesting.
Works of art.
I gave Mike the general specs of what I wanted, for Andy's engine (with automatic transmission), and he came up with the final profile.
We have that data.
I believe that his personal engine had a more aggressive profile, as I think it was a manual transmission car.
Works of art.
I gave Mike the general specs of what I wanted, for Andy's engine (with automatic transmission), and he came up with the final profile.
We have that data.
I believe that his personal engine had a more aggressive profile, as I think it was a manual transmission car.
That's your IP so we'll never see that and that is completely understandable.
I've read quite a bit about his efforts. Top shelf and sad about his passing. RIP Mike.
I was hoping someone who bought one of Mike's four manual transmission camshaft sets might have programmed them and would be willing to share the data.
I caught another episode of Engine Masters this morning. And when they were laying out the mustang V8 engine details they said the lobe separation angle was 110 deg.
I heard it said that is the sweet spot and was intrigued when the same LSA for Mustang V8 was mentioned.
I’ve been offered a set of three GT cams. The one missing is the exhaust for the 5-8 bank (which is also NLA from Porsche). What would be the best replacement for that? Reworked S3? Keep stock S4? Any other options?
I had a client who had some GT cams installed in his S4, before I ever saw the car.
It ran very well, once you got it moving and up a bit into the rpm range.
We installed a higher stall torque converter.
And it ran very, very well.
it's important to remember that it is extremely difficult to go too far wrong with 110 degree lobe centers on a naturally aspirated engine. (GT cams have that, exactly.)
Unfortunately, Porsche no longer has a complete set of GT cams....they are missing one exhaust cam.
.....There are ways around this supply problem.
A couple of ways, actually.....
Greg,
I installed GT cams in my S4 and I cannot agee more with you that it totally transformed the car. However once in a while the car stalls when coming to a stop on roundabouts or traffic lights and I am wondering if a higher stall torque converter might be a solution. Can you elaborate on the benefits and let me know if today you stock one ?
Geo did you change the computer chips to GT versions? they have a higher idle RPM,
also how old is the ICV and MAF.
The ICV could be corroded,
if you can spray some PB blaster into the feed hose,
this could remove some of the corrosion on the vane shaft
Did you replace the throttle shaft bearings with the new double O ringed versions,
as well as replace the TPS when you did the intake refresh
Geo did you change the computer chips to GT versions? they have a higher idle RPM,
also how old is the ICV and MAF.
The ICV could be corroded,
if you can spray some PB blaster into the feed hose,
this could remove some of the corrosion on the vane shaft
Did you replace the throttle shaft bearings with the new double O ringed versions,
as well as replace the TPS when you did the intake refresh
I did modify both S4 computers to GT specs by JDS and retuned the MAF as well. I have not refreshed anything on the intake as I had 0 problems before the upgrade to GT cam spec so I might well need a 'flagectomy' :-) Any idea where I can find the new double O ringed versions of the throttle shaft bearings?
I'll start by spraying PB blaster into the feed hose then.
Roger sells these bearings,
you need 4,
two for the flappy,
and two for the throttle shafts
NOTE the original bearings only have one side with an O ring, and these are by now crusty,
and will let oil pass,
this will fill the TPS with oil and cause it to not work properly.
hi, i actually had the cams made by dbias. 222°@1.00mm lift the same profile for in and exhaust. i wanted to have the base circle the same with the original, but because i used the S4 cams as base, i was not able to make the base circle the same to have the higher lift of GT profile. so the baes circle was cut down. So i decided to have inner shims on top of valve stems so that the original lash adjusters will work. cams are already installed and now i am working on the exhaust system. by the end of this year, i should be able to fire up and check the power. once i know the data, i can share my experience with you guys. if you have further questions, please feel free to ask. Cheers!
Bonjour Mitsu,
I get my camshaft regrinded by Dbilas. The camshafts code are : inlet 86B and outlet 142B. They made GT profil on S4 camshafts, keeping the same LSA.
I rigged them about 1,2mm at TDC for intake and exhaut is 1,0mm. They delivered the camshaft with 16 1mm caps to put on top of intake valves. Nothing for exhaust.
They work fine. I have more power after 5500RPM and I have less power below. I have to change the setting to see if I could get more power below 5500RPM without loosing at higher RPM.
I will provide more feedback after I will finish to play with them.
But if I can't find better, it is not a big deal. They are working good.
The sound the engine have from 4000 RPM to top end if fantastic!
I installed 24LBS injectors.
I set the idle like GT.
Hi Raphael,
Thank you for your feedback. Your cam setup seems very similar to mine. Have you done any power measurement ? I installed dbilas 222°@1.00mm lift borh on intake and exhaust. I am very curious what kind of power and feel I find with 5.4GTS engine, I will definitely do the power check and share the result with you. Cheers!
I’m bringing back from the US porken tools I bought to Roger so I will be able to easily play with the camshafts now!
I’m verifying power with my iPhone with an app that measure acceleration. Entering the weight of the car and air data I can get an estimation of standard power.
Maybe not as precise at a dyno but could show delta power from one configuration to another.
have a great weekend
Raphael
It is interesting. I have used the similar device to indicate the power output of the engine from acceleration rate. I have also measure the power using Dynapack. The result was pretty comparable. If the device you use measure the velocity by GPS and acceleration is calculated by differentiation of velocity data, then it is important to get a smooth velocity profile. Otherwise, the acceleration data becomes quite noisy and the power data calculated from the acceleration rate becomes less accurate. Of course, Cd, frontal area, weight data should be reasonably accurate. For that reason, it may be better to measure the acceleration under lower speed so that the influence of Cd etc is less. Let me know the result once you havve it. Cheers!
10-26-2023, 08:32 PM
anyone interested?
