reddragon14

Hey guys, I'm planning on building up a 383 with no power adders to produce around 500hp, because I would like to be in the 11's and able to drive it on the street and with 500hp I would have a good chance reaching my goal. So if some of you guys would be so kind and give me your build ups as examples that would be great if you don't mind.
Thanks, Logan

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http://www.airflowresearch.com/chevy_dyno.php

reddragon14

Thanks for the sheets, the only thing looking at the sheets are I can't use 93 octane but it would be easy to make the adjustments.

Orr89RocZ

iTrader: (20)

What gas do you have available?

383 with flat top piston is 11 to 1 compression in 64cc heads. Thats mostly 93 octane. 91 can be run with 10-10-5 to 1. Thats a slight dish piston but no worries you can still make 500hp.

Here was mine: 400whp/380wtq ran 11.47 at 118 with best trap of 119.1 in summer heat. 3450lb raceweight Irocz. 10.6's with 150 shot nitrous

All forged 383, eagle crank/rods/SRP pistons, flat top 5cc reliefs 11 to 1 compression
AFR 195 eliminators with 8019 spring upgrade, shimmed to 1.775" install height for 165lbs seat pressure.
Custom Bret Bauer Racing hydraulic roller. 286/306 230/245 .603/.613 w/ 1.6 rockers. 109 LSA. Comp Pro mag rockers and comp pushrods
Ported holley stealth ram, 58mm holley TPI throttlebody, 42lb injectors.
89 MAF electronics, first ran gutted MAF then eventually made my own 3.5" MAF, but ran the same both ways.
Hooker 2210 long tube headers, jethot coated.
4" single exhaust dynomax ultraflo muffler.

3600 stall, Edge racing converters. 3.42 gear/26" ET street tires for the strip.


Thats basically it. Strong motor for sure.

Two recent 383 builds here, one carbed/one FIRST TPI based that should make close to 500hp...the TPI one was dyno tested with carb setup and made over 500hp already.

https://www.thirdgen.org/forums/engi...-383-swap.html

https://www.thirdgen.org/forums/engi...195-383-a.html

This one may do it, but cam is alittle smaller than I'd like to see in a 383 for that power
https://www.thirdgen.org/forums/engi...ap-thread.html

reddragon14

Thanks a lot, what your running with out nitrous would be perfect. How does it drive on the street? Also did you have to put a different rear end under it or does the stock rear end rebuilt with stand the power?

reddragon14

btw 91 octane is all we have

Orr89RocZ

iTrader: (20)

Drove fine on the street. Very manageable. I set idle to about 950-1000 but it MAY handle less...it just preferred the higher rpm stability. 950-1000 is a good idle rpm with decent amount of timing. Being EFI it would have better manners than a carbed car would.

That thing cruised well and likely got 20mpg, although I'll never know since I never tested it but it seemed to behave almost like my bolt on L98 was which got 23-24mpg highway. It never overheated much past 185 deg with factory radiator and dual fans and 170 tstat. I loved that motor, but it is very loud with single 4" exhaust. But you can take it to 7K rpm and still have power..it peaked at 6250 but held flat to 6500 where dyno run stopped. I shifted mostly 6600-6800 and never lost ET. Great powerband.

I used a rebuilt 700r4 trans and it held power just fine. My rear was a stock 4th gen piece from a LS1 fbody. Held fine even on spray. continued to hold just fine on my twin turbo 401 motor that makes close to 700 at the tires but that car leaves softer than the 383 did, but still alot of power comes on through that rear and it held. A few other buddys have run 4th gen rears with success behind auto trannys and one through a T56 thats been 10.07 at 133 on a nitrous 406. Some friends of mine broke them with bolt on LS1 motors.

Its hit or miss but traction really kills the rears and hard shocks from manual trans clutch drops. Auto's are softer. Now an auto with a transbrake would be similar to a manual clutch...i wouldnt advise it.


EDIT: 91 oct can run ok in most motors. To be honest I drove my car with a mix of old 89 oct and some gallons of fresh 93 when I first started it up and it ran fine. If you keep conservative timing and proper air fuel, you can likely get away with 91 oct on 10.5-11.0 to 1 compression motors as long as the cam is decent enough to keep dynamic compression and cranking compression down some

reddragon14

so do you have to do any modifications to the 4th gen rear end for it to bolt up to a 3rd gen if the 3rd gen rear ends will not hold up?

Orr89RocZ

iTrader: (20)

its bone stock and bolted right in place of the old rear. Brake lines and all. There is a swap thread about 4th gen rears here that I made for my car and others have shared their experiences.

Your car being a 91 should have the later 28-splined axles as does the 4th gen rears. If the posi unit is in good shape it may hold just fine. You can try it and if it fails just swap a later year 4th gen rear in to get by. The 4th gens have the zexel torsen diff which is unlike the clutch type Auburns and eatons that some cars have. I think this gives them some strength and longer life.

Parasoth

iTrader: (1)

reddragon: I have the same problem as you, only 91 down here in 918, OK. But there IS a solution.

I discovered a thread on ls1tech about E85 mixing. http://www.ls1tech.com/forums/genera...xperiment.html

Apparently the formula for octane when mixing is as follows:

Gas Octane x ? (Gallons you put in car) + E85 rating (105) x ? (Gallons you put in car) divided by the number of total gallons you put in. (Gas+E85)

From what I have found, to get 93 you need to add around 15-20% of what you put in.

I'm cheap and only put $20 worth of gas in every week. This usually nets me 5.5 gallons. I will use 6 to leave me safe room for error and to account for any price differences (5.4, 5.7, 5.8 gallons etc)

91 x 6 + 105 x 1
546 + 105
651 divided by 7 = 93

93 octane!

Remember, don't top off your tank (And forget to put E85 in!)

10 Gallons of fuel:

91 x 10 + 105 x 2
910 + 210
1125 divided by 12 = 93.75 octane.

I have been using this in my 11.4 compression, modified heads/stock cam LS1 for about 3 weeks now and it's been perfectly fine. what I did was nabbed two 5 gallon gas containers, went to the closest E85 station for me and nabbed 10 fillups worth of E85. The first time before I started the car, I added the E85 first and then got gas. Now that it is mixed, I usually get gas and when at the house, dump in the E85 so I am not carrying fuel around in the back.

Here's a link to E85 stations around you. http://gasprices.mapquest.com/search...d=&sortOrder=2

Also not only are you getting 93 octane, since its 105 mix you can lean on it harder because it runs cooler. That thread up there is a really good read.

gbayfisher

Here's another one for you!

With the other two from Orr and this one, thats three very different builds with similar output
Good luck with the build!

https://www.thirdgen.org/forums/engi...ap-thread.html