If you mix oils 50/50, for example fully synthetic 10W30 and 20W50, is the viscocity going to be 15W40? I know that this logic works for gasoline octane but does it also work for oils?

 

Yes, I believe you are correct.

 

Any update on your race car. ??

 

yes, I finally dropped it of at the chassis shop to get my cage upgrade, tranny x-member and parachute installed.. Should get it back in 2 - 3 weeks and then it'll take me another 2 weekends to get the car ready...

 

Yes, That is an acceptable way of blending viscosities to get the oil pressure that you want.

Bet you're anxious to get back to the track. Our season is just about finnished here. The Halloween Classic, this week, at Norwalk is the final big event.

This winter we plan to back-half our car and put in a four link and 9".

Just can't seem to get the car to go any faster on a 10.5" tire and the IRS.

 

Blending oil is similar but the big difference is, viscosity is affected by temperatures, so when calculating the mix the end reading is based on "X" temperature. I had to do some fleet research a couple years ago and found the formulas and conversions to get very technical (physics it not my strong point). This data is from one of my contacts at the time.

SAE 30/SAE 40 blend - 12.6 cst@100c - (a heavy 30W)

SAE 20/SAE 40 blend - 10.8 cst@100c (a light 30W)

15W40/5W20 blend - 10.66 cst@100c 70.4@cst@40c - (10W30)

20W50/10W30 blend - 15.4cst@100c 118.3cst@40c - (15W40)

5W20/20W50 blend - 13.1cst@100c 91.2cst@40c - (10W40)

 

Cool, looking forward to seeing what you can get out of it.

Oliver, keep us updated. I have the itch going bad too........should have the motor finished in the new few weeks or so, ran into some machine work issues that set us back a bit.

 

Heard about your block issues on another board. Did you get them ironed out?

Still have the Fab 9 for sale? Now that the season is over I can start concentrating on the rear suspension. Still need to decide if we can work with a 4 link and stock frame rails or go full tub with big tires. If we go full tub, a 9 inch like yours would be the ticket.

 

We still have 1.5 months of the season remaining... The next season will start mid January.

BTW - I think that mid 8's should be possible with the IRS. Greg Eaton has run 8.50's on Tom's setup..

 

I have decided to keep it and make it fit in my car. We took some more measurements and with a little fabrication I should be able to run 16x33's

 

Winters are much longer up here. Tracks re-open in April if it stops raining then.

We've gone over 155 MPH and, I'm sure that we could get an 8.50 ET on a good day, and with good track prep. We bracket race here and with a marginal track surface we are just not consistent. Running full tilt we over power the tires after the 1-2 shift and it starts to spin. The only way that we can get good times is to take some power out of the motor and shift early. Seems a shame that we can't use all of the power that we have.

I also feel that the Tom's IRS, although very strong, is just plain using up too much horsepower. Cars with straight axles running the same MPH as we are are going up to .5 faster.

The IRS has served us well up to this point but for traction and efficiency reasons I think that a four link and a 9" rear end is what we need to step up to the next level. A back half would also help lighten the car maybe 200 lbs.

Probably also going to put in a funny car cage and certify the car for 7.50. I'm pretty sure that with a big shot of N2O we will dip into the low 8's or possibly high 7's.

Just don't see us doing it with the old IRS.

Any way good luck with your project and hope to see you back at the track soon.

 

What tires are you running? How exactly is your suspension setup? (front coils?, rear spring stiffness, what shocks?)
Look at Greg Eaton's car. He is sitting on the rear bumper with 9 inch wide ET Drags and has not major traction problems. I think that with a little suspension work and maybe different tires, you won't have those traction problems anymore.. If you aren't already running 29 or 29.5 inch tall tires, I'd do so. Taller tires = more traction. I noticed that when I went from 28 to 29.5 inch tires.

 

If you have ever watched 10.5 racing you will know that just because you can get a high power small tire down the track every now and then, or even a majority of the time, does not mean it is a bracket car.

That car will run 7's when it gets back halfed. How much tire are you going to try to get under it ?? If it were me I would try to get at least 32x14.5's. That is what I ran before I re-did the car. Are you going to run a 400 or a glide ?

4 link ? wishbone, anti roll bar ? chromemoly everything ?

 

Tires are 28 X10.5 Goodyear. Suspension is probably about the same as yours. This setup worked fine when we had the little motor last year. The IRS was perfectly happy running 9.90 ET @ 135MPH all day long.

Now, the problem is not on the starting line. Sixties are mid to low 1.30's with a good track prep. It does a nice controlled wheelie and carries the fronts most of the way to the sixty.

The problems we are having, start when the front wheels drop and the rear suspension unloads. This I know is probably caused by the excessively stiff spring that we have to use to get anti-squat during the first 60'. Shifting early to second (5500 RPM) and we still get tire shake. Shift early again (6000 RPM) into third tire shake goes away and it pulls hard all the way to the stripe.

Please bear in mind this motor makes peak power at 7400 RPM. We haven't even come close to using its potential.

The only thing that I can think of to get rid of this problem is an MSD digital 7 with traction control. Maybe this is Greg Eatons secret. I don't know.

If you have any other suggestions I would be eager to listen.

BTW you probably see better traction with 29.5" tire because you have 4.11 gears. We are running 3.70 gears with a fairly tight converter. The stripe comes up around 148MPH and 6950 RPM. Again not ideal but leaves some room for a 155 to 160MPH pass with nitrous.

 

What spring rate are your front coils? Rear monospring? Steel or Composite? What about shocks? I run Competition engineering 90/10 in front and QA1's set to 10 - 11 clicks in the rear. My front coils are 213 lbs/inch (250 lbs/inch after cutting off 2 coils) and my rear composite spring is 550 lbs/inch.
I do have a 4.11 posi but will switch to a 3.70 spool. My converter is not tight and I will run out of RPM with nitrous. However, when going to 3.70 gears, I will probably go back to 28 inch tall slicks.

 

As I said, same suspension that you have except for a steel 9 leaf in the rear.

It works good on the starting line but when the power comes in it shakes the tires.

You gotta remember we are trying to hook up with probably twice the horsepower that you are used to.

The IRS simply isn't working from 100 to 330'.

Also the local track makes a transition from concrete to asphalt at the 330' mark. This is always a slick spot and we try to have the car in high gear by that point.

 

Are you running at Thompson? Certainly very close to you. Ever go to Norwalk? A bit of a hike for you, but the track should be first class.

Oliver, sorry for the hi-jack...

 

E-mail Greg Eaton to share experiences with him. You are probably running about the same power level than he does..

He hasn't been on the forum in a while but you can try to e-mail him using the link below!

http://forums.corvetteforum.com/send...member&u=31016

 

No problem! Feel free to hi-jack my threads anytime

 

Yes, we are regulars at TRP. Saturdays are for racing the Vette, and Wednesdays are for the wifes 70 Chevelle.

Norwalk is great. It is about a two hour drive with the truck and trailer. We run a little quicker there. I think we ran 9.02ET @ 153 MPH last time there. Thats about 2 or 3 tenths quicker, and about 5 MPH faster than we usually go at Thompson. But the ET doesn't justify the MPH there either.