Suggestions on improving top end performance

Looking at the data from a number of passes and I think we're loosing some ET on the top end. Here's the incrementals

60' 1.23
330' 3.51
660' 5.36
1000' 6.95
1/4 8.29
MPH 166.8

Seems that the 8.29 is a bit slow for the 5.36 1/8 mile ET. MPH would seem to indicate a better 1/4 ET as well or do these numbers look OK?

Also the data is showing some wheel spin after the 60' and before the 1-2 shift (727 torqueflite). It's a four link car, wheelie bars and non-adjustable shocks. Car sits back nice and square on the wheelie bars at launch and the front wheels are back on the ground before the 60' mark. Wheels spin starts shortly thereafter for a bit and once we grab 2nd, no more wheelspin. Any hints on how to reduce the tire slip at this point?

if it was my car i would tighten up the bump on the shocks, in order to hold more pressure on the tires longer. At your ET you really need to get a good set of double adjustable shocks, it will make a big difference.


Joe

The tire spin before the 1-2 shift on a well prepped track is most noticeable in the data log but on a more marginal track, the car dances around and often have to abort. We want to step up the nitrous hit on the first stage but have to get rid of the tire slip before trying a larger shot. Adjustable shocks are on the to do list this winter.

Thanks for the input. It is appreciated.

I think shocks are highest on your list of needs.

Can you post up a scrfeen capture of the data log? Maybve shots with the RPM and DS speed and then one showing fuel poressure, afr and accel G's?

Hey Al,

Not quite that sophisticated yet. Using an MSD Grid controller and using the data from that currently. It's crude but overlaying shift points, timing, etc. with the RPM you can decipher when the tires are slipping. This is our first foray into this kind of ET so everything is still pretty new.

post a screen shot of the MSD review and let us have a look...

I just put 4 runs on my new grid set up and think it is going to be great!

Are you running any launch retard to reduce the wheel spin on a marginal track?

Cheers,

Arnie

I'm just the local village idiot Rick but at the et's and speeds the Green Ba$tard is running I'd think a set of good adjustable shocks should help with the wheelspin down track.Dave

Hi Arnie,

No launch retard as there is very little tire slip at the launch. It starts to spin right around the time the front wheels come down which is 60' or less. I'm at work right now and don't have the Review file here but I can upload a screenshot later this evening. Shocks are on the list as the first thing to try to help with the issue. The performance in the big end is a little tougher to nail down as the data from the Grid is not extensive enough to really show anything of use at that point. I suspect it is a little fat at the top but haven't had the opportunity to play around there much yet. A racepak logger along with O2 sensors and driveshaft sensors is probably the next things on the list.

Dave, you're right about the shocks. Mike's pocket book has been taking a beating getting the car together and the repairs this year so shocks kinda got pushed back. We'll see how it goes this winter as to what upgrades Mike wants to do but there's another project in the works so who knows?

You might recognize the car Arnie. Haven't even removed the old SK license plate.

Here you go. Green is engine RPM, blue is launch, red is shift and purple is engine timing being pulled as the nitrous comes on. 1st stage is right at the hit and 2nd stage just before the 2-3 shift. You can see the RPM dancing around just before the 1-2 shift.

Quote:

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Looking at the data from a number of passes and I think we're loosing some ET on the top end. Here's the incrementals

60' 1.23
330' 3.51
660' 5.36
1000' 6.95
1/4 8.29
MPH 166.8

Seems that the 8.29 is a bit slow for the 5.36 1/8 mile ET. MPH would seem to indicate a better 1/4 ET as well or do these numbers look OK?

Also the data is showing some wheel spin after the 60' and before the 1-2 shift (727 torqueflite). It's a four link car, wheelie bars and non-adjustable shocks. Car sits back nice and square on the wheelie bars at launch and the front wheels are back on the ground before the 60' mark. Wheels spin starts shortly thereafter for a bit and once we grab 2nd, no more wheelspin. Any hints on how to reduce the tire slip at this point? [/quot


IMO, from the numbers, I think you have it backwards. Your top end performance is fine. Your soft on the 60 ft. and 330.ft and okay on the 1/8th After that your numbers are great or better then they should be by .25 IMO , but you are running a power adder.

Good point. We had considered the 60' was a little soft and should probably be in the high teens but you're right. I probably was looking at it backwards so maybe with a shock change and adjustment to get rid of the spinning it should improve the lower end numbers enough to lower the overall ET.

thanks

I think you are loosing a lot in the first 60 feet... My best 60 foot is 1.18 when the traction was actually good at SIR, but it runs 1.19 - 1.20 sixties if track is just average...

My review looks similiar with peaks and valleys in first and second due to tire slippage, but climbs stright in third gear.

You are much faster than my cuda, so you should be able to pick up your 330 IMO.

Good luck!

Arnie