25 replies to this topic

[cmonkey99]

So I raced my second weekend at Utah Motorsports campus this year. Renting the car from somebody. 

 

I have 14 years racing under my belt but this is my first year in the car. Nothing is known about the engine save for it was built by Ti Speed at one point. 

 

I ended up getting runs on both 1st and 2nd place drivers in the race but even in the draft, they were already pulling me by the end of the straights. Was wondering what might be the issue or is my motor just too old and tired to keep up? Both were 1.6s, I'm in a 94 1.8. Could refreshing the valves or rings be enough of a fix?

 

- Carter

[Jspaid142]

We can speculate all day, but the best thing to do is dyno the car at a shop that does SMs often, that way they can tell you if the motor is competitive or not. Keep in mind things such as hubs & brakes can cause extra drag which doesn't necessarily show up on the dyno but will show up on the track. 

 

Just because they pulled on you in the straights doesn't necessarily mean your motor is tired, they could just be getting off the corners faster than you

 

-Joe

[James York]

The first thing I do when I think my motor may be going south is do a leak down on all the cylinders.  It's a quick easy way to make a first pass determination if you have some bad valves or rings.

[MPR22]

So I raced my second weekend at Utah Motorsports campus this year. Renting the car from somebody. 

 

I have 14 years racing under my belt but this is my first year in the car. Nothing is known about the engine save for it was built by Ti Speed at one point. 

 

I ended up getting runs on both 1st and 2nd place drivers in the race but even in the draft, they were already pulling me by the end of the straights. Was wondering what might be the issue or is my motor just too old and tired to keep up? Both were 1.6s, I'm in a 94 1.8. Could refreshing the valves or rings be enough of a fix?

 

- Carter

Two things could be the problem,

 

1  You are racing West Coast 1.6 cars which are notoriously cheated up and your car could be just fine.  

2, You are racing a 94 SM the biggest underdog car in SM racing, even in top condition you could not keep up with the 1.6s.

 

That is all tongue in cheek.

 

Do what James said, start looking for the simplest problems first.  Leakdown, parasitic drag.  If those aren't an issue start looking at 12v sources, fuel pressure,  timing, sensors.....

[Bench Racer]

Carter, the basics are you in a NA 1.8 had issues with two 1.6's.

Are you racing NASA, SCCA, ???

At which track did this stuff occur?

Were there any 99 plus cars in the race group? If yes, how did you fair with them?

[Todd Green]

I can point you to the dyno that just about all the local cars have been on and we can get an idea if you want to go that route.  You have my email.  Also as I previously sent you in email, have you checked the restrictor plate in your car?  NASA allows a larger plate this year (47mm instead of 45mm).  Finally along with hubs/brakes, you should also check alignment and tire pressures which can also affect your straight line speed.

[Johnny D]

You should have the nut behind the wheel checked out too. Check the video/data or somebody behind you.

Never know.

Just saying.

J~

[Todd Green]

You should have the nut behind the wheel checked out too. Check the video/data or somebody behind you.

 

When someone who's been racing for 14 years says, "I ended up getting runs on both 1st and 2nd place drivers in the race but even in the draft, they were already pulling me by the end of the straights." I'm going to take them at face value that they understand the concept of exit speed.  But like I said, we have a dyno at the track, compression and leak down tests can be done, check the timing and fuel pressure/AFR etc. easily enough.

 

Though re-reading your post you are renting the car (from Larry?)  Shouldn't you be talking to the person who is renting it to you?

[SaulSpeedwell]

Let's ignore the draft for a minute.

 

1 second at 35 mph (51 fps) and 1 second at 110 mph (161 fps) vary by ... well ... 110 feet.  So, if two cars are turning identical laptimes with identical power but are 1.0 seconds apart on the track, then the lead car should *appear* to pull you by 110 feet from 35 mph to 110 mph.  If you are a half second behind, then it is 55 feet. 

 

Even with two cars running identical laptimes, the cars will always "bunch up" in the slowest corner and "stretch out" at the end of the fastest straightaway.  This is why every driver except the winner regales his buddies at the pizza party with a story I'm sure none of us has ever heard:  "I catch him in the corners and then he just motors away!"

 

I'm not saying you aren't being outmotored - I'm just making a friendly reminder to "subtract out" the relation of time/speed/distance in reviewing the data and your observations. 

 

When you get a run, catch the draft, pull out, get alongside and THEN he "just motors away".  In that case, check your alignment, your brake drag, your dyno tuning, and THEN yell at your engine builder

[chris haldeman]

+1 on above post!! I am constantly trying too explain this fact too drivers. Just did yesterday while watching a customers video. I simply pointed too a fix spot on the track and counted gap. Amazingly the driver was not catching under brakes and losing on straights.

[Ron Alan]

^^^^This concept(not understanding it)sells more engines than you can imagine! "I out brake EVERYONE!" ..."it must be my motor, no other explanation!"

[Bad Rusty]

Thanks Ron, now I need to find a new excuse.  I'll look elsewhere on the site, I'm sure I'll find something..

 

^^^^This concept(not understanding it)sells more engines than you can imagine! "I out brake EVERYONE!" ..."it must be my motor, no other explanation!"

[cmonkey99]

Thank you for the replies. Forgot to check the thread!

 

I would come out of a corner with more exit speed than the car in front, get close to his bumper and then watch him pull away even though I was in the draft. Both cars were 1.6s. I reviewed the video just to be sure I wasn't making excuses for myself and that it truly was the motor. 

 

Wish it was my driving! Sure a lot cheaper to fix! haha

 

More details:

I'm racing NASA in Utah. Renting the car from somebody who runs HDPE and doesn't really have an interest in making the car perform better (other than handling). I just make changes/upgrades in exchange for rental fees sometimes. I've been looking into buying a '99 car but unsure of what I'll be doing next year.

 

- The car has the new 47mm restrictor.

- dead neutral toe, front and back. Checked twice during the weekend with a good string guide on level scales. Originally had some different settings but put it dead neutral since I am getting killed on the straights. 

- 35psi hot on Toyo RRs

- Hubs and brakes seem to have little or no drag. 

- Springfield dyno exhaust put on before this weekend.

 

Todd, I will be in touch soon.

[Johnny D]

I'd love to see that video. Maybe we can learn something from your driving.

J~

[Keith Novak]

In my experience with my ’95, a 1.6 will do better at the end of a long straight, especially if you get into 5^th gear in the 1.8.  Countless times, I’ve been able to pull a gap on a 1.6 at the beginning of a long straight, only to have them pull along side and then pass me at about 100 mph.  With a very fast 1.6, I can generally stay with them if I can keep glued to their bumper, but if not, they will probably gap me.  That's with a decent motor but not a stump-puller.

[Steve Scheifler]

Are you certain that the car you drive as the correct diff ratio? I know of several "regional" SM owners who never bothered to switch as required, at least one had no idea of the rule change until I told him last year. Since the owner's priority was not SM he may well not have bothered with the effort and expense.

[cmonkey99]

Not sure on the diff ratio. It was raced in SM the year before but I have no idea if they changed the ratios. Unfortunately my data acquisition doesn't have RPM for me to just do the math.

 

Cylinder pressures are as follows:

178 psi

160

169

147

[av8tor]

not only low, but quite a range.  My '99 with the completely stock 96,000 mile donor motor  is 205, 202, 203, 205 

[Steve Scheifler]

I have seen large diffrtences from gauge to gauge, so much so that I rarely bother except as a quick check for one or two way off from the others. But regardless of absolute values, yea, those are all over the place. Do a careful leak-down to identify the primary points of loss for each.

[Mark]

Not sure on the diff ratio. It was raced in SM the year before but I have no idea if they changed the ratios. Unfortunately my data acquisition doesn't have RPM for me to just do the math.

 

Cylinder pressures are as follows:

178 psi

160

169

147

Throttle blade open or closed? How many strokes?