mark kibort

why wouldnt I? Not enough self control?

I like my spring pad idea. are you still running stock trannie and clutch?

what kind of power did yours come out to.

mk

John Veninger

I'm in the 550+ club
Tranny is "stock" 89S4, but with cryoed gears and shafts and a tighter lsd.
I'm running the Tilton clutch setup like Anderson.

Did run the DD with Andersons old beefed up pressure plate at Sebring and Summit Point last year.

mark kibort

Im going to get one of them! I just cring at doing the clutch again, but i could use the shop lift and it wouldnt be so bad. at least those headers can stay on while the lower bell housing drops down. actually i should do it before I forget how to do it (again, for the 20th time!)

mk

mark kibort

Bill,

It looks as though Ill be getting 200 miles on the Holbert machine this weekend in visiting Mark and Joe at Laguna. On Tuesday, around 1pm, Im going to the dyno. If we can just plug in your o2 sensor and do a run on the dyno, that would be good. I would like to do a 1/2 throttle run, (or .75 throttle just as the TPS engages), a full throttle to 5k and then a 5500rpm run if everything looks good and the HP is not just plumeting. Depending on the AFR, I would like to turn the fuel regulator up or down .5 turn to see the effects on pressure. (depending on where it is) my guess it probably is pretty close right now.

Im wondering if its better to have the AF meter plugged into a laptop or into the Dyno machine. Im betting on them being able to screw their o2 sensor into the bung in the header. are they all the same thread types? Im sure he must have an adapter if its not. I can always go to the other dyno in San Jose called "DynoSpot Racing" He has a tail pipe meter. Hmm. available tomorrow for a dyno?



mk

drnick

mark - is it possible to drop the clutch with the devek headers in place? ive got the level two set and it looks really tight but i wasnt sure.

JKelly

Don't stroker motors generally produce more torque, or at least more torque down low for the same amount of horsepower as an SC'ed motor?

Bill Ball

All O2 sensors are the same thread. If they have one, let's go with that.

Dyno tomorrow?? Let me know when. I'm in the middle of re-installing my SC, but it can wait.

Black Sea RD

Hi John,

Didn't your diff break at Sebring, which was your first time out with the new stroker engine?

Hope all is well,
Constantine

John Veninger

yes

mark kibort

From the dyno, the torque is (on the fully modified stroker) ranges between 450and 400 rear wheel torque.

I was checking out the old devek stroker curve and it was 407hp and 450torque.
It fell off a lot faster and actually had more torque down low, where i (or any racer) will never use it.

I plotted a graph with Anderson, Devek's old engine , and the Holbert stock engine to see where the big changes will be. actually, the entire curve gets bumped up 100ft-lbs of toruqe the only time that my new stroker will put as much force on the clutch as my old Holbert motor, is near 6000rpm, where that value would have been max torque at 4000rpm

mk

John Veninger

Go look at Ott's graph. TQ is much higher than 450 on fully modified strokers.
The use of the throttle bodies and short stacks was to move the torque up the rpm scale to help some gear crushing at the lower rpms.

mark kibort

I think Mark A's with the CF intake is pretty neutralized. 450 peak torque, but hp in the 510 range. One thing about my stroker is that im still using the stock intake , so i can leave flappy closed to reduce the 3700 to 5000rpm torque levels and not effect top end hp.

mk

GregBBRD

Mark:

Good luck with that.

John Veninger

+1

mark kibort

Got a last minute appointment with a dyno shop Ive used a few times over the past 10 years. He has a working tail pipe mounted wide band O2 sensor system.

The results were interesting, good, and a little bit of a let down, but at the same time reassuring and exciting. So, here is the good and the bad.

Torque was 420 at the rear wheels, while the hp was at 365. (I think someone predicted this!)

More of the good news was that the mixture was set pretty good from the start, and all we had to do was richen it up by .5 turn on the RRFR, which drowned the motor at 10:1, and then back it off by 1/4 turn to reach the range of 13:1 down to 11:1 at the top. So, good that it is safe and bad that its a little fat up top.

I had some good indication of 400rwhp, from 60-80mph, but hadnt taken it to 6000rpm to see what the next half of the 60-100 test would look like. Well, on the way home, still, 1.9 seconds 60-80, but the next 20mph to 100mph was 2.5 seconds. Not much faster than my fastest runs with the stock holbert car of 3.0 seconds. Actually, Im starting to really like the freeway dyno. Its pretty cheap and reasonably accurate. So the car is at 4.5 sec, 60-100mph. Not bad for only a stroke and slight bore increase.

Now the question is what is keeping the engine from getting the 400rwhp that Anderson and Fan got on their stroker with the stock heads (i think they had stock top ends and no mods and 400rwhp) Anyway, the devek machine made 407hp, and had some head work and ran on pump gas. max torque was near 450.

could it be mixture? cam timing too advanced as porken tool has indicated?
cam timing difference between the two sides?

It could something simular to the knock sensor issue that Anderson saw. however, it didnt seem to come into effect until 5200rpm. I think a stroker with 400rwhp should have torque in the 450range.

Anyway, I'm still pretty happy. This thing is REAL fast. Ill have an average of 70 more hp to play with, coming from 120 ft-lbs more torque at the midrange rpm.

time for some shark tuning and cam timing checking.

We will get it figured out.

Until then, its a dose of Amsoil and its off to the races.

Ill post the dyno run

EDIT: Here are the dyno runs. The progression started out with 1.5 turns rich. It was kind of lean. we turned it up by .5 a turn. that buried the fuel ratio in the rich range. So we leaned it up by .25 a turn. AND, if you noticed, we started the dyno run at a lower rpm, as the fuel ratio seems to require about 400rpm to stablize, no matter what the fuel setting. (going from closed loop to open loop.)
I also included something ive never done before. a partial part throttle run . This half throttle run produced more HP than the original engine.
The last dyno sheet is when we started the dyno run at 2800rpm. after a brief rest. The car was real hot on the first few dyno runs.


mk