A friend of mine is planning to build a drag only car. His dad recently passed away, so he is planning on using his dads old(in very good condition) dirt modified motor. It is a 383 stroker, that runs 13 to 1 compression.(those are the only details I know of the motor) It used to be wound up to 7000 rpms for almost a complete race. Our main concern is the octane that will be needed to power this motor? Can anyone estimate the power that will be put out of this motor, though I am very brief on the components? Also, anyone that has experience in this type of racing that could give me insites on what goes into these motors. All info would be greatly appreciated.
Thanks Travis

Everything about that motor will be like a drag motor.

------------------
1978 Z-28 purchased new by me -$6750
Click here (http://f1.pg.photos.yahoo.com/ph/someonehasthisid/detail?.dir=/d752&.dnm=aefd.jpg) to view present state photo
Look above for glory days.
1994 Formula
1982 350 S-10

It may fall in the 450 to 500 range. You'd want to run 114-118 octane with this type of motor. Power though will really depend on the heads you are running and the camshaft duration and lift. Also, depending on how long the track was it may or may not be a good 1/4 mile motor. 7000 is not real high for a modified.

------------------
70 SS 454 CI Dynoed 684 HP, 702 TQ All Aluminium Fuel Injected Small Block , plus 200 - 500 HP NX nitrous system.

[This message has been edited by Rick WI (edited December 23, 2004).]

The cam is pretty much the only thing needed to be changed. The duration is probably in the 106 lobe center area, I run mine installed @ 102. circle track grinds are not really good in drag applications IMO (Been there done that). Other then that the CR is almost perfect for Methanol http://www.nastyz28.com/ubb/wink.gif . I run almost 14.3:1 on methanol with my motor.

Depending on the class the motor was used in (Street stock/IMCA Mod.) depends on what the motors are put together with. They can range from $1,500 beaters to $25,000+ motors. We really need to know the parts/cam profile to give an estimated HP #. Remember stock parts can go 7,000rpm with heads/cam -->for a while http://www.nastyz28.com/ubb/smile.gif

[This message has been edited by 70 Z UC (edited December 23, 2004).]

i race dirt track and lot of the imca modifieds we see are methonal burning motors and that compression you stated is right for methonl. the usual horespower is around 450-500hp with a very tight LSA of 104 or less. the engines are designed to run up towards 8500rpm but are not a long life motor.majority of the modified motors are 360-410 cubic inch displacement.the average laps per race night would be 5-10 laps idling "mud packing" ,5-8 laps "hot laps" ,5-8 laps "heat races" , 25-30 laps "main event".so add that up to about 12 race nights per year and that motor is done it'll need a rebuild.i bet you that motor was built with claimer engine parts in it.

------------------
1972 chevy camaro ss 350 sbc 425 hp/356 @ the wheels,350 trans,373 gears,daily driver with restification in progress for that old school day 2 look ------- future plans- turning it into a baldwin motion Z30 clone
"IF IT'S TO LOUD YOUR TO OLD"
-------------------------

I'm suprized Rick would suggest so much octane for 13:1, you certainly won't have detonation issues at that level.
At the very least, you should do a leakdown test on the engine and have a look at the bearings. Personally I wouldn't even turn the key until I magnafluxed the crank and rods. Our guys running late models around here get roughly 2 seasons out of their cranks before they start cracking. The timing set, especially the cam sprocket, also can have a short lifespan and will start to lose teeth if a small harmonic was used. Being a 383, if it's externally balanced, that crank will see some flexing at 7000. Valve springs are also a well abused part on an oval track engine.
You would be wise to check the engine out first, it could save you money down the road. I hope it makes good power for you and provides years of entertainment. http://www.nastyz28.com/ubb/smile.gif

------------------
Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

Im running a dirt track cam in my Car i love it i have a narrow, violent powerband!
105 LCA!
Mine is built with claimer parts!
Man i love my motor thing pulls hard!
35-40 mph on the street hit it and you cant hold in the gas youll hit a ditch!

[This message has been edited by Mwilson (edited December 24, 2004).]

<font face="Arial,Verdana" size="2">Originally posted by rustbucket79:
I'm suprized Rick would suggest so much octane for 13:1, you certainly won't have detonation issues at that level.
At the very least, you should do a leakdown test on the engine and have a look at the bearings. Personally I wouldn't even turn the key until I magnafluxed the crank and rods. Our guys running late models around here get roughly 2 seasons out of their cranks before they start cracking. The timing set, especially the cam sprocket, also can have a short lifespan and will start to lose teeth if a small harmonic was used. Being a 383, if it's externally balanced, that crank will see some flexing at 7000. Valve springs are also a well abused part on an oval track engine.
You would be wise to check the engine out first, it could save you money down the road. I hope it makes good power for you and provides years of entertainment. http://www.nastyz28.com/ubb/smile.gif

</font>

I only suggested due to the total lack of data available. No indication of aluminium or iron heads, tiny combustion chamber with flat tops or big combustion chamber with big arse domes, cooling control is also important. I thought it would be much safer starting high and working down than filling with 100 octane, detonating it and taking out a head gasket, ring land or beating up bearings. At the least I'd use 110.



------------------
70 SS 454 CI Dynoed 684 HP, 702 TQ All Aluminium Fuel Injected Small Block , plus 200 - 500 HP NX nitrous system.

And here I thought you had a big power secret here Rick, dang!!!
It's amazing what people will get away with, there are people running 12:1 at the track all the time on pump gas (did it myself, poor quench and all, years back), running 110 octane on a 13:1 engine then backing it with a 325 horse nitrous kit, etc.
My favorite in recent memory is an oval track guy that was having detonation issues on a lower compression late model car. It took a while to figure it out as most that run the class mix 110 with pump premium 50/50 with no issues and here this guy is killing gaskets, detonating Wiseco pistons, having heating issues and such. I finally get it out of the guy, he would run a bazillion hot laps, qualifiers, heat and dash races. THEN he would throw a fiver of 110 in the fuel cell for the main event. Gee buddy, you don't think the damage was happening during all the racing you were doing prior to the main event? Funny how some people think.

------------------
Custom Auto, your source for quality machine work, cores and new parts at competetive pricing right here in British Columbia 1-888-563-4050
A Canadian, EH? (with a 10 second street car)

No secret, just a lot of pain and suffering from the season before with a guy running pump gas in a Street Stock shop motor we built for him FOR FREE. He was running pump gas and detonating the hell out of it and taking the gaskets and pistons out of it. We tore that motor down 3 times then went to his house one day and took a fuel sample before we figured it out. EXACT same issue as you had, only he didn't even mix. This Mo Fo was such an inconsiderate SOB to do this I can't believe we didn't shoot him. To this day he swears he always ran 110. We still keep part of the fuel sample in the dyno room.

------------------
70 SS 454 CI Dynoed 684 HP, 702 TQ All Aluminium Fuel Injected Small Block , plus 200 - 500 HP NX nitrous system.

Duh, I forgot to say that they are domed pistons, with big combustion chambers. I think in the 70 cc range. They are iron heads, and the whole bottom end is forged. Unfortunalty, my friends dad passed away in a motocross accident or I could have all the specs for you. I do know one thing this motor was put together with the best parts of the time(10 years ago). I hope this helps?
Thanks Travis

[This message has been edited by 78RSCAMARO (edited December 24, 2004).]

Mine are domed pistons camel hump heads 93 octane?

(its worked so far!)

Mwilson,

Please tell more about your dirt track cam and motor combination so we all may learn a thing or three..

I'm asking b/c of the little supposed 264/246, 108/108, .498"/.498" gross lift solid cam I am going to try in my 283 motor if I ever make it... He, He!! Already bought the cam tho, so it will get made some day??

Please come back..

pdq67

I cant teach anyone anything, i learn everyday, all motors are different and have different intended uses everyone has their own opinion of streetable some people like broad powerbands others narrow, if your building it yourself be open minded to every option, but know what your goal is and determine what you need after you hear what everyone else has tried if something someone else did helped you great. Ive always been the one to try different stuff just to try I've slowed my car down more times than made it faster just expirimenting and i like sharing the info i have from things that have worked or not for me hopefully im done experimenting for a while im happy with my motor its just what i wanted, maybe now ill get a real paint job and some professional bodywork.
heck if i had the money i spent on carbs, cams, intakes and exhausts id have my dream
camaro!

to me streetable is pump gas, exhaust, dot tread, wont overheat in traffic.
heck if i could afford one a those 10.5 cars id drive it to work.




[This message has been edited by Mwilson (edited December 26, 2004).]