Holbert Car cam update. Two MORE teeth found after 4 race weeknds after oil change
09-30-2005, 08:31 PM
#121
Three Wheelin'
Originally Posted by mark kibort
Here are the dyno runs.
The first graph is the flappy being held vs the flappy not working. here you can see the effect of the flappy used over the entire range, vs not working.
The second dyno graph run is the flappy being held open over the entire run with the '85 cams vs the Holbert cams with flappy not working (notice the first hump is not there with the flappy held, but a HUGE increase in torque in the midrange to 5krpm, and then who knows if it helps or hurts to redline.
The interesting thing here is the shape of the curves are pretty close, even with the new cams. looks like ive lost hp in the max hp range as well as max torque range. pretty uniformly. the dyno operator said that the Air fuel meter was not working properly, so the ratios are real lean, but supposed to be not a true reading. (sure seems like that could be the problem though.)
I changed the fuel filter and will maybe kick up the fuel pressure a half turn just in case.
flappy had a cold solder joint on the dianostic cut i made when fixing it the first time. now its working!
let me know if you guys think i should try advancing the timing at least on the passenger side, as the holbert cams were timed at 2mm both sides. plus the cams had more advanced intake lobs anyway. maybe i should use the GT spec of advance and see what it does? has anyone tried this?
MK
The first graph is the flappy being held vs the flappy not working. here you can see the effect of the flappy used over the entire range, vs not working.
The second dyno graph run is the flappy being held open over the entire run with the '85 cams vs the Holbert cams with flappy not working (notice the first hump is not there with the flappy held, but a HUGE increase in torque in the midrange to 5krpm, and then who knows if it helps or hurts to redline.
The interesting thing here is the shape of the curves are pretty close, even with the new cams. looks like ive lost hp in the max hp range as well as max torque range. pretty uniformly. the dyno operator said that the Air fuel meter was not working properly, so the ratios are real lean, but supposed to be not a true reading. (sure seems like that could be the problem though.)
I changed the fuel filter and will maybe kick up the fuel pressure a half turn just in case.
flappy had a cold solder joint on the dianostic cut i made when fixing it the first time. now its working!
let me know if you guys think i should try advancing the timing at least on the passenger side, as the holbert cams were timed at 2mm both sides. plus the cams had more advanced intake lobs anyway. maybe i should use the GT spec of advance and see what it does? has anyone tried this?
MK
10-03-2005, 02:38 AM
#122
Rennlist Member
Thread Starter
no, the cuves for fuel were not correct, as the system measuring A/F was not working properly. ingor the fuel. my pipe is still full of black soot, and plugs look normal if that was the curve, i would have problems! (vs my old curve)
Originally Posted by 928SS
I'm no expert, but I suspect AF could easily be the culprit - a glance at louie's pages show gains of 15rwhp from a mixture tweak, and I gained 40rwhp just going from .75lambda to .85lambda... if you are lean, I'd expect the same kind of power drops on the other side of optimal too...
10-03-2005, 02:56 AM
#123
Rennlist Member
Thread Starter
So, Im on the way to the dyno and 60 to 80mph is still 3.6 seconds in 3rd, and another 3.6-7 from 80 to 100mph.
ON the way to the track with a full load of race gear and tires, usually, i run 60-100mph in 6.2-3 seconds with all the extra weight (normal is 5.9) . Im running 6.7 to 7 seconds Now!! 60-80mph in the 3.8 second range and even in 4th gear, its in the 4.8 second range ( very slow!) car even sounds a little funny. SO, i get to the track and practice, the car has a running exhuast vibration that sounds like the C5R ALMS car (thumpy??) not a screamer and high pitch whine like usual. So, i run as hard as i can in practice and with real good almost new SpeedGt toyos, a 1:42. then i qualify, 1:41.2. the car is a pig out of corners and i have no acceleration. THEN, i adjust the timing of the one cam set at 1.7mm vs the driver side of 2mm after talking to some engine experts at the track. (one of them, the mechanic for one PRC organizers, Jay) I move the passenger side advance by 3-5 degrees (since 10 degrees equals about 1mm, i figure 3-5 degrees would get it back to almost even with the passenger side, which is at around 2mm and at max advance for the pulley holes.
as a note, the holbert cars cams were both set at 2mm!
Then, i start 'er up with 10min left for grid. running like crap.... OH, forgot the coil wire! start' 'er up again and it comes to life . reves nicely, and i go for a padock spin. car is totally different. sound of exhaust is back to a scream, and is not flat like before. roll up to grid and race!! run my fastest time ever!! (1:40.2 Same as 3 years ago with Hanson when i was putting down 335rwhp!) good tires, engine is back to original HOLBERT specs and I am excited!
So, in my opinon, you want some big power, advance your cams. at least match the timing of the cams left to right. the engine growing, belt slacking thing is BS. it cost me about 15peak hp and who knows the total power lost as the entire curve was shifted down!
Packed up on the way home , 60-100mph . back to 6.2-3 and 60-80mph in the 2.9seconds range
Now, Jim........ its now a bone stock S4 with a set of 85 cams!!! (and headers )
although we really dont know what the heads look like yet, and hope we never have to find out!
what a car!
Thanks guys,
Mark
race recap coming, if you car to hear how the ole holbert car beat a top 10 World challenge touring car (john prall)and almost beat one of the vipers loosing the drag race after a hard 17 lap battle, to finish 3rd out of 55 cars, 35 in class . Lots of door bangin'. great video
ON the way to the track with a full load of race gear and tires, usually, i run 60-100mph in 6.2-3 seconds with all the extra weight (normal is 5.9) . Im running 6.7 to 7 seconds Now!! 60-80mph in the 3.8 second range and even in 4th gear, its in the 4.8 second range ( very slow!) car even sounds a little funny. SO, i get to the track and practice, the car has a running exhuast vibration that sounds like the C5R ALMS car (thumpy??) not a screamer and high pitch whine like usual. So, i run as hard as i can in practice and with real good almost new SpeedGt toyos, a 1:42. then i qualify, 1:41.2. the car is a pig out of corners and i have no acceleration. THEN, i adjust the timing of the one cam set at 1.7mm vs the driver side of 2mm after talking to some engine experts at the track. (one of them, the mechanic for one PRC organizers, Jay) I move the passenger side advance by 3-5 degrees (since 10 degrees equals about 1mm, i figure 3-5 degrees would get it back to almost even with the passenger side, which is at around 2mm and at max advance for the pulley holes.
as a note, the holbert cars cams were both set at 2mm!
Then, i start 'er up with 10min left for grid. running like crap.... OH, forgot the coil wire! start' 'er up again and it comes to life . reves nicely, and i go for a padock spin. car is totally different. sound of exhaust is back to a scream, and is not flat like before. roll up to grid and race!! run my fastest time ever!! (1:40.2 Same as 3 years ago with Hanson when i was putting down 335rwhp!) good tires, engine is back to original HOLBERT specs and I am excited!
So, in my opinon, you want some big power, advance your cams. at least match the timing of the cams left to right. the engine growing, belt slacking thing is BS. it cost me about 15peak hp and who knows the total power lost as the entire curve was shifted down!
Packed up on the way home , 60-100mph . back to 6.2-3 and 60-80mph in the 2.9seconds range
Now, Jim........ its now a bone stock S4 with a set of 85 cams!!! (and headers )
although we really dont know what the heads look like yet, and hope we never have to find out!
what a car!
Thanks guys,
Mark
race recap coming, if you car to hear how the ole holbert car beat a top 10 World challenge touring car (john prall)and almost beat one of the vipers loosing the drag race after a hard 17 lap battle, to finish 3rd out of 55 cars, 35 in class . Lots of door bangin'. great video
Originally Posted by Louie928
You could retard the cams 3 to 5 degrees. That should help the top end above 4000 rpm. Try 3 runs with more fuel and 3 runs with less fuel and check results. With the engine warm, check compression on the 1 - 4 bank, and the 5 - 8 bank and see if one side is much different than the other side. Different hot compression can indicate that cam timing isn't the same on one side as related to the other side. The side with lower compression indicates that side is retarded as compared to the other side.
10-06-2005, 01:39 PM
#126
Rennlist Member
Thread Starter
did you notice that the euro cams from 84ish, had intakes open at 9 degrees ATDC (vs 3 for GT) and that the exhuast cams open 47 degrees BBDC (vs the 30 degrees for the GT) with durations slightly longer and comparable lifts, maybe porsche was on to something that couldnt work for emissions or power or somthig on the S4s or other 32valvers!
certainly shows that advancing could be an option, plus those engines cams have no fine tuning and are matched too! (as far as timing)
Mk
certainly shows that advancing could be an option, plus those engines cams have no fine tuning and are matched too! (as far as timing)
Mk
