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Topic Review (Newest First)
04-26-2012 09:50 AM
ap72 It will run fine with aluminum heads and 10.2 compression, provided it is tuned really well and that you're running those 4.10s.
04-26-2012 09:08 AM
my87Z
Quote:
Originally Posted by High School Hot Rod
I'm going to order up 4.10's from summit. That is as high as I'm willing to go. I'll keep the short stickys for the track and 28's for the road. I'm looking for a th350 or 400 trans, shifter, and a 3500 stall. I've done some more playing around with a dynamic CR calculator. With a .040 overbore, 72cc heads, slugs .026 in the hole, and a gasket .015 thick w/ 4.100 bore my static compression is about 10.2. Now calculating... (more like a total estimation imho) the intake closing ABDC seems to be controversial. I did not add the 15 degrees or so that is often suggested. Assuming I use the 248/252 cam Fbird88 suggested my math looked something like this. The advertised intake duration is 276, you divide this number by 2, 276/2 = 138. Take 138 and add the LSA to it, 138+106 = 244. Take 244 and subtract the sum of 180 and the ground in cam advance. I believe this cam is ground straight up so. 244 - (180 + 0)= 64. So my intake valve would close 64 deg ABDC. Plug this in to a calculator at the lowest altitude the car will see at 2800ft, and presto i get a DCR of 7.68. Did I do this right? With a quench of .041 and aluminum heads woud it run just fine on 91?


yes that is how you would do it, listed below i have found the DCR calculator that has helped me out the most.

http://www.projectpontiac.com/ppsite...tio-calculator
04-26-2012 01:04 AM
High School Hot Rod Thumpin455 you didnt read my last post. But can anyone tell me if I calculated the DCR correctly. I just used that cam as an example. I'm looking for heads and my budget only allows good iron heads a bottom of the line aluminum heads. If i know i can get my DCR low enough i would go for some irons. Thanks
04-26-2012 12:19 AM
Thumpin455 You want to keep the 3.42 gears and you dont want to lighten it from the almost 4000lbs, but you want to run 7s?

The fastest way to do that is with a relatively mild 455 Pontiac. Seriously. A small chevy isnt going to do it, there just isnt enough torque there. Maybe with a huge shot of nitrous and lots of stall, but it will be an overheating pig on the street. The only small chevy that would do it is one of the LS engines, the gen 1 isnt going to make it happen on your budget.

A 454 built right would do it, but it needs to be cammed for idle to 6500 with an emphasis on the low and midrange. You have lots more weight with the BBC, so you need to make more power to run the same time.

Gut the car, lighten the hell out of it, get it down to 3100 to 3300 and then you will have a much easier time getting into the 7s.
04-25-2012 10:37 PM
High School Hot Rod I'm going to order up 4.10's from summit. That is as high as I'm willing to go. I'll keep the short stickys for the track and 28's for the road. I'm looking for a th350 or 400 trans, shifter, and a 3500 stall. I've done some more playing around with a dynamic CR calculator. With a .040 overbore, 72cc heads, slugs .026 in the hole, and a gasket .015 thick w/ 4.100 bore my static compression is about 10.2. Now calculating... (more like a total estimation imho) the intake closing ABDC seems to be controversial. I did not add the 15 degrees or so that is often suggested. Assuming I use the 248/252 cam Fbird88 suggested my math looked something like this. The advertised intake duration is 276, you divide this number by 2, 276/2 = 138. Take 138 and add the LSA to it, 138+106 = 244. Take 244 and subtract the sum of 180 and the ground in cam advance. I believe this cam is ground straight up so. 244 - (180 + 0)= 64. So my intake valve would close 64 deg ABDC. Plug this in to a calculator at the lowest altitude the car will see at 2800ft, and presto i get a DCR of 7.68. Did I do this right? With a quench of .041 and aluminum heads woud it run just fine on 91?
04-25-2012 09:51 AM
ap72
Quote:
Originally Posted by 67-4-fun
running 4.56 gear with a 26" tire in an 1/8 mile crossing the traps at around 93mph your rpm will be around 5400rpm, to drive it on the street at 60mph your rpm will be around 3500, if you were to run a 28" tire, then you would be crossing the line around 5200 rpm.. hope this give you an idea as to what kind of rpm you may running.. crossing the traps or finish line at 93mph on average will get you about 7.60-7.70 ET in an 1/8. reason as i pick 93mph is because most of the guys that ive raced with running sportsman class run a 7.50 or slower time to be that class, so i know by looking at the time sheets, that around 93 is a good average + or - a few mph.... you can adjust with tire size a bit by going up to help calm the rpms down on the street, but you sacrifice the drag strip a bit, You should really determan what percentage you plan on driving on the street vs the drag strip and set up gearing and tire size to the bigger percentage or more what the car will be mostly driven.. As for weight of your camaro, i guessing the car itself weighs more like around 3300lbs or so
If you run that 4.56 gear with a .70 OD then it ain't so bad on the street... you'll need some suspension work to hook up in first gear on a 700r4 with 4.56 gears though.

Don't be so caught up in throwing money at the engine, the rest of your drivetrain means a hell of a lot. You could probably hit 7's with all factory parts except for a mild cam and headers when it came to your engine.

There are a lot of slow 500hp cars out there because they didn't set the drivetrain up to match the engine.
04-25-2012 02:18 AM
67-4-fun running 4.56 gear with a 26" tire in an 1/8 mile crossing the traps at around 93mph your rpm will be around 5400rpm, to drive it on the street at 60mph your rpm will be around 3500, if you were to run a 28" tire, then you would be crossing the line around 5200 rpm.. hope this give you an idea as to what kind of rpm you may running.. crossing the traps or finish line at 93mph on average will get you about 7.60-7.70 ET in an 1/8. reason as i pick 93mph is because most of the guys that ive raced with running sportsman class run a 7.50 or slower time to be that class, so i know by looking at the time sheets, that around 93 is a good average + or - a few mph.... you can adjust with tire size a bit by going up to help calm the rpms down on the street, but you sacrifice the drag strip a bit, You should really determan what percentage you plan on driving on the street vs the drag strip and set up gearing and tire size to the bigger percentage or more what the car will be mostly driven.. As for weight of your camaro, i guessing the car itself weighs more like around 3300lbs or so
04-24-2012 09:58 PM
79bird Hey man im in high school too and im also trying to build a fast car on a small budget(1979 Firebird) just like yours. From what i've learned, some basic things that cost almost no money can make your car faster. One thing I did was that I changed the rear differantial fluid. I found out it hasnt been changed ever, and when i pulled off the differential cover, i noticed that it was all thick and sludgish. Once I put some Royal Purple 80w90 in it, it ran like a dream and instantly got a feeling of more power. Something else i found out was that the calipers were all pushing against the rotors, which obviously causes friction. Also, those gears will not work, as F-Bird 88 suggested your gunna need higher gears, but i feel 3.73-4.10 would be good. Also, ive found ALOT of parts on Craigslist. I even saw a set of Vortec heads brand new for only $300. Just my 2 cents good luck and i look forward to seeing how it goes. TRUST me on one thing, weight makes a HUGE difference! Cut as much out as possible. If you wanna take it 100% just gut the interior and pick up an aluminum bucket seat ($120ish). Obviously exhaust and headers or no exhaust system at all!

Ive found this as well!
http://www.carcraft.com/techarticles...s/viewall.html
04-24-2012 09:26 PM
my87Z Go with the 72 cc heads, and you can get away with around 8.5:1 DCR. My old set up was about 8.7:1 DCR and I was able to run it on 93 octane
04-24-2012 08:46 PM
High School Hot Rod I agree with fbird88 that i do need more gear. summit sells a 3.90's for my 8.5 and i think that would be about ideal for me, but 4.10's sound tempting. My goal for my car is to eventually to be a nice prostreeter street/strip ride. I do have acces to race gas but i really dont want to go that route. 91 at highest. I've been playing around with a dynamic CR calculator and the cam would have to be way radical to get a dynamic CR around 8:1 which to my understanding is pump gas worthy. But I could use some help deciding whether I should use a thicker head gasket and sacrifice quench distance, or use 72cc heads and give up quench area. But 91 is a definite must.
04-24-2012 05:58 PM
my87Z i understand why Fbird is telling you 4.56's (not that i agree), the 4.56's will utilize more of your motor while running down the track, but for your case i think they may be a bit much. i could be wrong but i dont take this as you want to have a more strip style car but would like a street car that will be raced at the track from time to time.

when i say that the shorter gears will utilize more of you motor i mean that one of the main ideas of drag racing is to use every bit of motor that you can. so you want you car to be running through the traps in it's final gear at it's max rpm ei if you shift at 6500rpm then you want to running through the traps at 6500rpm. using this idea since seem only interested in the 1/8mi then the shorter the gear the better. but when you want to drive this vehicle on the street and not be running 3500+rpm at 60-65mph then you have to find a happy medium.
04-24-2012 05:48 PM
my87Z
Quote:
Originally Posted by joelster
The tune, the plug heat range, the cylinder head material, the amount of timing, the density altitude (he's way up) all have a bearing on whether it will live on pump gas. I'd bet money he'll be fine. My car is at 11.77-1 static and it purrs on pump 93.


He's got a pretty tight budget, but anything will be better than those iron dinosaurs he's running now.


Totally agree. Makes no sense to go with a 4.56 gear and THEN buy a taller tire to knock it down a bit, like guys are recommending in the other thread. In fact I would leave it alone and see if it makes it to the 7's just the way it is.


A cam like that would be really good here. I'd wake it up a little with some 1.6 rockers and the appropriate springs. It should pull a little higher than 6k though. Maybe you didn't have enough cylinder head to feed the motor?


i used 1.6 rockers on the intake and 1.5 rockers on the exhaust side to help even out the dual pattern cam, my heads were DART 200cc platinum's with decent cleaning up done. the motor pulled past 6000rpm but my peak hp (512) was made right at 5900rpm.

i never said that it was impossible to run 10.8:1 on pump gas, but as you mentioned, a lot goes into making it run on pump gas. my previous set up was 10.4:1 and could run on 93 pump gas. my current set up has 11.2:1 and does not like pump gas.
04-24-2012 07:39 AM
ap72 You'll need a clutch and trans that can handle the power... easier said than done. Maybe consider changing the trans to a well built 700r4 and tuning up the engine first. Even with the gears you have the trans and stall can make a huge impact.
04-24-2012 12:07 AM
68NovaSS Your duplicate threads have been moved into this forum and merged. Please don't double post.
04-23-2012 09:23 PM
High School Hot Rod Alright well to clear the air the the car currently has a manual three speed transmission. The weight of the car was also a rough estimate, I am a bigger guy at 6'3 230. And I'm not looking to get deep into the 7's just want to get into the 7's. I know I'm wanting to have my cake and eat it too. I'm will to strip the car for weight loss to some degree. I dont need big stereo, back seat, front fender wells. I don't know how how much that will save me but it might be worth a try. I can do 4.10's anything higher is just not going work for what i want. If this is a factor that puts me in the low 8's so be it. I like my car and like to drive it and dont plan to replace it with something lighter.

I took it to the track once but only had an open 3.08 differential at the time with some crappy street tires. With one tire a fire for half way down the track my best et was a 9.1. The next day race a nice old man let me race his 71 chevelle that ran consistent 7.70's. After that i was hooked enough said.
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