How much does horsepower factor in lap-times at your local track? I see a lot of people building 1000+hp twin-turbo engines, but I don't see where/how they could possibly use it all.

I was watching Keith's El Camino videos at BIR again, and thinking about how my car will compare at certain parts of the track. Later this year, we'll probably both be on the track at the same time, I'm just wondering if I'll be able to keep up. (would be cool to shoot video of each other)

He has way more horsepower than I do, so I know he'll get down the 1-mile straightaway a lot better than I will. I've got a better weight-balance (SB chevelle vs BB el camino) and a little better suspension than he had,(SC&C stage II vs. B-spindles, all rod-ends vs. poly in the lower rears, etc) Now he's going to have the coleman spindles, and both have equal rear suspension.

It's got me thinking that with my ~300hp, I'll be at a severe disadvantage on a big course especially with the long straight, but on a short course, my weight balance should actually allow me to be faster.

For those of you who have run an open-track day, how did horsepower factor in your lap-times? We talk about your suspension's effect on lap-times all the time, but if you don't have the power to get down the straights, the best suspension in the world might not seem too impressive if your getting burned by the guy with bad geometry, weight balance, and a monster of a motor.

that's why my Twin Turbo BB will be all aluminum :p ;)

We road race a 64 Nova with a stock suspension setup and it's not easy to tell where power and handling land unless you're comparing apples to apples. On the local courses we can lose the Factory5 Cobras on the straights but they get us in the corners.
On the open road we dominate our class, which includes Mustangs and Corvettes, but it mostly comes down to the driving and tuning.

When you cannot control on-throttle corner exit over steer anymore, you have too much HP, up until that point the more the better for W2W. That HP can make the difference in the back stretch.

A little off subject but i've always enjoyed being able to drive right underneath the guys with the big motors as they pushed to the top for a lack of handling and then they have to try and run me down on the straightaway. But circle tracking doesn't always relate to road course driving. A lot of it has to do with driver ablility and throttle/brake control.
Stomping on the pedal may look cool, but its not always the fast way around the track.:p

I'm thinking my ~300hp won't hurt much on the curvy part of the track, where you probably don't use much more than that anyway, but I know I'm going to lose a lot of time on that mile-long straightaway.

For a road race motor, you want something with a somewhat of a flat torque curve with peak horsepower a little higher up the chart(don't want a 5,000rpm limited motor. You want to always have power, the less down/up shifting you do the less time you will waste. if your car is lacking on HP by the time you get going, it will be time to brake again, you want to be able to come off the corner, accelerate quickly, and brake/downshift(heel/toe) again. I would say you could make up for less horsepower with really wel lthought out gearing. THe problem with this is every track is different. If you can gear the car so when you come out of turns that you can stay in a good gear and power out of the turn you will be good to go. Don't worry about W2W I highly doubt anyone here or around is modifiying their car to the strict guidelines its gonna take to enter and compete in actual racing. You will be getting passed up on straight aways but thats probably about it.

Now saying all that, your barely 300hp in a 4000ilb beast is going to be a little dissapointing. I would do everything I could to gain some torque outta that motor, and gear the car accordingly. Maybe some nice 1 5/8 headers and a nice long runner intake manifold.

BTW most of these 1000hp twin turbo blah blah, are mostly poser cars. There are some people on this board who will go to the drag track to take advantage of the power, but most of these hard-ons on the other sites(cough cough) are just building these things for show off/bragging rights/wow factor. I'd love to see a competitve twin turbo big block with 1200hp anywhere on the track. However this isn't saying I wouldn't love to feel/ride in a car with one of these beast motors! Turbos are definetly fun, but I think most people are kidding themselves with anything over 700hp. Even charlie said the mule was too overkill for the track, not to mention all the weight that stuff creates.

that's why my Twin Turbo BB will be all aluminum :p ;)
are automobiles even gonna be around by then???? :D :beers:

Now saying all that, your barely 300hp in a 4000ilb beast is going to be a little dissapointing. I would do everything I could to gain some torque outta that motor, and gear the car accordingly. Maybe some nice 1 5/8 headers and a nice long runner intake manifold.A cam and head-work are in the plan, but just not feasable this year. The suspension and just getting the LT1 in the car has my budget tapped out. It's pretty easy to get 450hp from a N/A LT1, but any more than that usually takes a lot of money and a power adder to get.

I figure the 300hp will be good enough for my first few times on a road-course, to be sure I have the necessary skills to keep it on the course first before I give myself much power to play with... gotta be honest with myself - I've never pushed a car that hard before, and I don't know how well I will do.

I think for a full weight chevelle, 400-450hp with a 6500 redline would be all you'd need to have decent RR engine. That's how I designed my setup. I wanted a 'mid 12 second' engine that could handle some revs and run all day on pump gas.

A cam and head-work are in the plan, but just not feasable this year. The suspension and just getting the LT1 in the car has my budget tapped out. It's pretty easy to get 450hp from a N/A LT1, but any more than that usually takes a lot of money and a power adder to get.

I figure the 300hp will be good enough for my first few times on a road-course, to be sure I have the necessary skills to keep it on the course first before I give myself much power to play with... gotta be honest with myself - I've never pushed a car that hard before, and I don't know how well I will do.
I would just throw a supercharger on there, screw the heads/cam. For the money (prob even find a supercharger used) you will get the most power from a charger. Although personally i prefer N/A. You should be fine at first with the motor you have, but I can almost bet after the first day you will be wanting more power :)

but I can almost bet after the first day you will be wanting more power It'll be after the first time he has to wave me by. :D

Keith, I'll just hold you up for a few laps like that pesky ZR-1 that was in your way. ;)

Maybe you could bump-draft me down the straight to help me out? :D

are automobiles even gonna be around by then???? :D :beers:

ouch...
let's only hope... ;) :boring:
Worst comes to worse, I'll set it up to run alcohol....

-Todd

Don't forget, if you don't have the skill to modulate too much HP on your own there's always retrofit electronic traction control!

The amount of HP put down is controlled via the right foot. Get good with the right foot and you can handle a lot of power, however some engine power delivery curves lend themselves to better roadcourse use than others as they're more forgiving.

Another problem IMO besides HP vs. Chassis issues (and driver ability, both to drive the thing and also know his limits) is as HP goes up heat management issues become a big problem-- radiator size, EGT's, oil temps, intake temps, and overall underhood temp; you have to deal with all of them. Cooking wires sucks, as does baking your oil, and so does overheating your intake and detonating the thing from out of control underhood temps.

Given a roadcourse goal I'd honestly prefer a well sorted naturally aspirated setup, the heat issues are a lot more manageable. Turbos under sustained use can easily cook things via radiated heat from all that hot plumbing. Superchargers don't have the "tons of hot pipes" problem but they'll still have high EGT's just like the turbo setup that can cause not only underhood temp issues (which can lead to detonation) but also tulip exhaust valves under sustained heavy use. Also with forced induction you need to make sure your intercooling arrangement is up to the task of sustained track day abuse and won't heat soak on you.

When I track my car I plan on swapping pulleys to de-boost the engine. This will keep intake temps down to help fight detonation and also allow me to run more timing to drop the EGT. My current 15psi setup is way fun on the street and dragstrip but it would be really hard on the engine for a sustained 20 minute thrash session. 5-7 psi will still provide plenty of power and give the engine a much better chance of survival.

The overall track makes a big difference too, as does the driver's skill. Years ago in the Ferrari club inexperienced drivers in their new Testarossa's could not come close to the lap times my Dad turned in our lowly 308 GTB-- even though the TR's had about a 200hp advantage (although a 450lb disadvantage.) The TR's had the advantage on the straights but we'd eat 'em in the turns. Given a more "open" track layout though I'd put my money on the TR's, but for the tracks we ran on driver skill was a much bigger factor than sheer HP.

Remember, the REAL fun on a roadcourse on an open track day is found in the turns, and you don't need a *ton* of HP for that-- just enough to get you up to your maximum achiveable entry speed and enough to power you out of the turn. If you're enjoying the straightaways more than the turns, seek help (and a dragstrip.) Disregard above advice if you're in a competetive event though. :p

Troy

I completely agree with regards to forced induction type devices, those guys have nothing but trouble on hot days come mid afternoon. Heat management is huge issue with asphalt temps approaching 150* at west coast tracks.

let's only hope nobody saw this post.............

-Todd

I have had my Chevelle on the track a few times now at Willow Springs (when it had a 4L60 tranny; don't go there if you road race) and a few times now at Thunderhill. It is very clear that HP is of limited use and handling is everything. Enough power will help in controlling oversteer but too much power (second gear in turn 5 instead of 3rd gear) will just get you sideways.
The car has a ZZ4 (350) motor with first Gen fast burn heads, HOT cam and 1.7 rockers with a TKO 5 speed and 3.70 Ford 9" rear end. RWP is about 360 at 5600 rpm with Rev limit at 6000. I keep it between 3500 and 6000 on the track. I have 255/50/17 BFG on the rear and the same size Nittos on the front. I need more rear grip as oversteer is the problem so I am looking for new rubber. Oh yes the suspension is Global West all around with Willwood 12" on the back and 13" on the front. My weight with me in it is about 3550 lbs.
I have not had heat issues but I did burn up a power steering pump. I now have a cooler on the steering lines and that seems to have solved the problem.
I think if I had an even 400 RWP and better rubber it would be about right. I would have to tub the rear to get any more power to the ground.
Last track day I kept even with a 992 Porche.. he was surprized.
I would like to see more Chevelles out there. Things like Hondas don't seem able to run with me at all but Lancers and WRXs do fine.

Ron

You shouldn't have to tub that 69 to get a bunch more tire under it,Ron. Some DOT 275 fronts and 285 rears should do the trick. Dennis is running those sizes on his 68 at those tracks with good success.

I think for a full weight chevelle, 400-450hp with a 6500 redline would be all you'd need to have decent RR engine. That's how I designed my setup. I wanted a 'mid 12 second' engine that could handle some revs and run all day on pump gas.

That's the combo I'm shooting for too,Brian.

I'm definitely going to have to upgrade all of the coolers,though.

Any suggestions as to size and back space? How about tration rating? I think a 30 (Khumo 710s) is too low (I want to drive on the street and be able to afford it) but the 400 on my BFGs is too high (but they last forever).

Ron

My Sumitomo's have a 160 tread wear rating. They have good grip and seem to be lasting fine.

I hear the Falken RT615 is OK, the Kuhmo ASX is supposed to do well also although I have heard rumors of chunking when allowed to get too hot and not properly shaved first. An acquaintance of mine is running Toyo RA1'a on the street all the time (he also recorded a .99g pull on the skidpad).

Correction noted

I believe RA1's are toyos not yoko's. My dad has them on his porsche and he loves them, but I think they have like a 80 treadwear rating, but they even work decent in the rain.

Any suggestions as to size and back space? How about tration rating? I think a 30 (Khumo 710s) is too low (I want to drive on the street and be able to afford it) but the 400 on my BFGs is too high (but they last forever).
Ron

I think the wear rating on my Kumhos is 100. They're the stickiest street tire I've ever run and have been on the car for over two years & still look fresh. My next tires will be Michelin Pilots. I have had excellent luck with them on both my ZR-1's and Michelin is one of the few tire makers that offers a 335/35/17 rear. Can't really run anything much narrower because my rear wheels are 17x13's.

A buddy of mine races his 924 Porsche in SCCA. He's done equivalent (and more) upgrades to the suspension and brakes, and as much as he can do to the engine to stay "in class". He's running a 2.0L 4-popper, non-turbo - best guess is he's in the mid/high 200's for HP, but not much (comparitively speaking to a V8) for torque - but a 7500+ redline.

He can out-gun 911's & 911 Turbo's anywhere on the track EXCEPT the straights. Due to nearly perfect 50/50 weight distribution, a lighter car, better power/weight ratio he can out brake and corner the "better" car. This translates into entering "hotter" & tighter, braking later/deeper, and exiting lower into the corner.

The 911's deal with this by coming around on the "high-side", and out HP'ing/Torquing on the exit - literally like he was going backwards - until the next corner where he'll make up the difference (sometimes.... it's cumulative).