Roots VS Screw

We are currently running a 16-71 littlefield hh modified by DMPE. on a 540 Oddys KB Olds configuration in a 2500lb 3speed bruno lenco auto Pro mod Door car. Spinning the blower at 30-40 % over depending the track. we have been a best of 4.27 1/8 6.60 1/4.
Which the times are okay but not really competitive enough for are area.

But the thing is now we might have the opportunity to go to a D rotor Screw setup. But know nothing about Screw blower racing no tune ups etc..
But Also Feel like the roots is kinda holding us back from getting in the low 4s high 3s

Should we try to make the switch and get rid of the roots ? What changes would have to be made first ? How hard would it be to learn this setup fuel system etc... ? How much e.t. should we gain on a mild tune up ? not trying to run 3.60s as we are running on a budget would be happy with low 4.0 3.9.

Thanks

 

206D on a BBC

We made the switch a few years ago in our dragster, we picked up about .35 sec from 6.35 to 6.00, w/o making any other changes, at the same boast 35 psi at 8000 rpms,
The key for us was to get the fuel system set up correctly, saves a ton of headaches!!!! On our set up the more fuel you can run through the hat the better, Lonnie Houde was the guy that got us dailed in, maybe worth a call?
508 776 4898

Just my 2 cents

Butch

 

we run the same engine with a 1471 Oddy's do us a very good job / what boost are you getting and how good or bad of air ? where do you race? what car new old chassis?

 

I have a Pro mod car 2570 lbs with hemi, torque conveter car, kebelco k11 supercharger with some mods. We have gone 3.89 at 188 1/8 mile. very low budget deal. I kinda want to try a screw blower deal but it takes a lot of money to change. and lot of testing to get it right so i am going to stick with it and try to tweak a little more out of it. I think there is more left. And unless You want to go run at The ADRL it competitive

 

roots

Talked to a guy with a KB olds lencodrive out of Louisiana that went 3.81@185 at 2600lbs with a mert 16-71 and very high overdrive.Says it goes .90's easily at 8500 rpm or less.

We're in the middle of the switch and it's expensive and difficult on a Chevy. I'd say first step is see what you can get out of your roots.Our Superman paid for about half of a bare expired D-rotor.

 

Yeah, after all the smoke clears, the cheap part of the switch is the blower. When you get over that hump, everything else nickels and dimes you to death (if you want to call $1,000 here and $1,000 there nickeling and diming). Once you are there though, you won't have to worry about going back.

I was running just about where you are and I could of spun it a little more and maybe got another 10th out of it but to me it wasn't worth the hassle. That was on a 14-71 that was 53% over and I could have gone to 57%. You look to have more room to spin it faster, just keep track on your manifold temp so it doesn't get too high.

On a side note, I am changing the trans and converter too and when I was talking to Coan about it, they said just by updating the converter from what I had to current technology would have gained me two 10th's by itself. Add that to the pickup from spinning it faster may be something to think about. Converters and pulleys are a lot cheaper than the whole screw package where you will probably have to get different pulleys anyways. Just my two cents.

Tom

 

That guy is giving you misleading info on that 3.81 and .90's

 

3.81

Shawn maybe he meant 1600 lbs

I see alot of the screw blower stuff going away anyways. Seems more and more classes and big money races will let on the roots cars run.

 

.81 that's flying for a roots. I think Ken Thomas out of Texas has been .83 with 18/71 AJ481x. Not sure of the OD.

 

Well we sold are Roots setup over the weekend. We feel that we made the right choice for the long run. We think this is gonna make us more competitve for the area we are in as most the races we run here are no rules anyway. And now were gonna try and shop around for a screw setup and gonna talk to Lonnie Houde this weekend at the PBIR Shakedown race to lead us down the right path.

Then Hopefully its ADRL in April at PBIR XTF!!

 

psi

Better be able to run low .60's to mid .50's and big money!!!!!!!!!!!!! best of luck!!!

 

3.81

After some clarification i'd say that 3.81 might be a hot dog wrapper. I was there when Thomas went a low .80 and he had a lot more blower than mert ever built. I think the roots record is a .79 out of Commisso.

 

The PBIR race XTF is just to try and make the show since we live right here.We were hoping to dive in the 3.90s for some local stuff and trailer a few folks.Thanks for all the advice keep it coming.
Doug

 

pbir

Millen is the man to beat that car will run .70's and ulsch is right there. If Lonnie is helping that is awesome he knows his stuff!!!!!

 

pbir

hey doug you need to keep the rods in her before you try to run the 3s
just meassing with u hope to see u there . nothing better than local boys
wipping up on million dollar operatons LOL
chris

 

I saw Ellis Vial had his C blower stuff for sale