before i go changing pistons
 

just curious, my shortblock still isnt assembled but the parts were for a n/a build originally. but now i have the dyers 871 i wanna use so.


with my 310 72 cceheads and ross flat tops my 455 is 11.6ish cr which is less than ideal but i wonder, with pulleys to make 6 psi could i get away with it.

with e85 and a bug catcher converted to fast xfi and a good blower cam" solid roller" could it be done or should i figure on ordering a set of dish pistons to get back around the 9.1 mark?

That is a bit much for boost, were the rings file fit? Were they filed for boost? Boost pistons have the ring lands set down a bit too. I used regular forged pistons in a turbo build and lifted 2 ring lands. That was at 9 to 1 on 12 psi (pump gas)

Talked to a couple boost guys,quench not that important,put a thick gasket and run it.Tom

file fit is the plan for the rings and the ring lands are set down i was gonna use with nitrous, everythings still in boxes. i seen butler sells cometic gaskets in different thickness but wasnt sure.



i wonder what the effective cr of ur 9.1 cr was vs what mine would be with 6 psi and 11.5/6

Stan Weiss would be the one to ask on here.

i hope he chimes in here......i cant get the search function to work on the phone version

I’d go with a thick head gasket also! Also keep timing down.


GTO George

This info came from Tom V. and he doesn't like the .090-.120 clearance. He said it tends to cause detonation. I ran .145 down the hole plus 35cc dish with Marty's sealing ring with a 61cc heads to get 8.8 to 1 compression.

Assuming the below engine parameters: Wallace Racing Calculator.

Engine Bore = 4.181"
Engine Stroke = 4.210
Deck Height = .004
CCs in the head = 72
Valve Reliefs = 6.6
Head Gasket Thickness .041"
Head Gasket Bore Diameter = 4.250"

Wallace Racing says you would be at 11.64 Compression Ratio.

So to get to 9 to 1 compression ratio you would need a (Wallace says 8.96)
you would need a Head Gasket that was .170" thick.
FOUR TIMES AS THICK AS THE .041" THICK GASKET THAT HE HAS RIGHT NOW.

RIGHT, BET THAT SUCKER WOULD REALLY SEAL UNDER BOOST. NOT.

Personally I would stay closer to 8.5 or 8.75 to 1 compression ratio and be able to add boost at a later date by using the PROPER parts vs a bandaid super thick head gasket.

Tom V.

All you would need is to get the compression in the 10’s with e-85 and you’ll be fine!


GTO George

I have to agree with Tom on this,just too thick for this application,maybe a 100 gasket but not this much.Tom

i can change pistons if i need to since its not together yet....i already gotta take the crank in to be cut for a 2nd keyway. not sure if that will change the balance or not but if it dont then i was just trynna keep from buying new pistons and having to rebalance if i could make it work. ive read on yb of alot of guys running 6 psi with e85 and higher compression but just not sure if that goes for pontiacs too.

You put the correct pistons into the engine (while it is apart right now) you have a lot of room for growth with the boost system vs a bandaid with a high failure potential just to get to 9 to 1 compression ratio.

Send a PM to Charlie66 as he has been running e-85 with boost for years, He has run as high as 39 psi, He makes 750+ HP out of a 1/2 of a 400 engine (4 cylinder pontiac engine) with 4 more cylinders he would make 1500 hp out of a 400 cid engine on e-85.

HE can give you some very good advice on running a E-85 engine with boost on the street.

Tom V.

With e-85 you can run higher compression with no problems.

GTO George

You know what’s nice about running a little more compression is that you can still make HP while running less boost and spinning the blower less which is easier on the crankshaft! Just a thought!! ;)


GYO George

What he say's
I'm running an 8-71 with 7:98:1 on pump gas with 10 LBS of boost.
I pop a couple head gaskets but now I have a timing boost controller
that will make the difference and I plan on spraying mine too.
If you want some of my info call me 269-832-8122 and I'll help as much
as I can. Charlee 66 has good info too.He give me some good information.

GT.

With 9 to 1 compression and 6 lbs of boost your compression would be around 12 to 1 with 11.5 compression your looking at about 15 to 1.
Roots blowers are not turbos asking the wrong/right questions will get you the wrong answers!

GTO George

Work with Blueghoast and Charlie66 (once you get the right pistons in the engine) and you will be fine with e-85 fuel and whatever boost you decide to run.

And as was posted, a timing controller helps keep the new head gaskets in the engine performing properly. Be very careful with the timing though. Talk to Charlie66 about the reasons for that deal.

Tom V.

1,500 HP at 39 lbs of boost.....why so much boost? Im making around 1,400 at 11 lbs of boost!


GTO George

Since the Butlers and Travis Q (as well as Marty Palbylin, in 1996) run high boost (that is 45 to 75 on a typical engine
and the Tractor Pull boys with the diesels are over 100 psi of boost with their stuff, it is not worth my time to explain the difference between a 88 or 91 mm Turbocharger and a 8-71 roots blowers capabilities.

You have a large engine, you have a poor efficiency supercharger (50-55% typically) and you don't spin the thing very high rpm so you make 11 psi of boost pressure and run low 8s. Your supercharger will live for years racing at those boost levels. (unless you do something stupid).

Charlie66 could run 38 psi of boost pressure on a 400 cid engine and make 300 more hp with his small engine vs your 525 cid engine. Which is 125 cubic inches bigger just by adding more boost pressure vs what you run).

Marty could run 6.96 with old school diesel turbos in 1996. It is now 23 years later and you are happy running low 8s and making a lot of passes with your combination. Marty was in the mid 40s on Boost Pressure if I remember correctly.

Mahovitz with a 281 CID engine and high boost 75 psi range runs in the 5s with a door car in the quarter mile. Your Roots system on his 281 cid engine would be a POS.

So read some books on Turbochargers George and then post up and I will try to answer more of your questions on the difference between the two boosting devices. If I explained a Turbo Map to you, then you would understand that a turbocharger (TO BE HIGHLY EFFICIENT AT MOVING THE AIR - must to be over 70% efficient) and the impeller has to spin 75,000+ rpm vs your Roots deal spinning 7500 supercharger rpm.

Tom V.

Sounds like your double talking.....that’s ok you just answered my question! LOL!


GTO George

For some people when they don't understand, it is always double talk. LOL!
Typical answer but expected.

How about this George.

Since you are now a Turbo Expert as well as a Roots Expert,
What is the difference in these three compressor maps?

Tom V.

Tom, I asked a question and you answered it by not being able to answer it.........let it go.
Back on topic!

GTO George

Ok I just can’t let it go..........what does Butler, Marty P and different size turbos have to do with me and making almost the same HP with only 11 lbs of boost compared to the 39 lbs of boost and 1,500 hp you said Charlie will make at 400 cubes?
......because that whole post made NO sense at all!

GTO George

The bigger the turbo would make more power per psi. Charlies turbo is tiny compare to ur blower. I made almost 1265 hp at 15 psi and my turbo was on the smaller size which is a 91.5 mm with a 1550 hp rating. I need a 98 mm for my 482 and that is rated at 18-1900 hp. But I want to drive it on the street so I wanted a small one. If I wanted to make a big power on lower boost, I just need to put a 106 mm on it and I believe it will match ur combo but that is just an example. But the turbo shines when u up the boost! Not a lot of hp loss driving it unlike the blower combo. Not arguing but stating the facts. Look at Daddy Dave at SO! He said he will never put a turbo on his car and look at his combo now. Twin turbo just like everyone else. The only one left is Megalodon and just a few guys and few nitrous cars. But turbo is the way to go for big power based on the cars running it. But what do I know. Converting to Turbo is just hard on a Pontiac due to the head design exhaust we have. This is why a lot of people are converting to LS.

Daddy Dave switched to twin turbos because he needed more HP and could not fit a BIGGER pro charger on it (no front end room if there was he would have seeped with the procharger) he didn't want to get a different car so he had no choice but to go to twin turbos.
As for Pontiacs head design we have the Warp 6 and DCI's RA5 heads!


GTO George

With my small blower set up (compared to a 12-71 or 14-71) all I can make (boost wise) is 11.5 lbs and I have to spin it almost 30% over (which is a lot for a roots blower of that size) to do that, even with that I'm making upwards of 1,400HP. So boost wise I'm maxed out...........i need a BIGGER blower. I couldn't imagine what my engine would make with a 12 or 14-71 on it......well over 2,200HP! Remember its not the size of the blower or how much boost can make its what you can do with what you have.....ive been working on my combo for a while! A lot of people just turn up the boost as oppose to working on a certain combo....not always the best thing to do.


GTO George

If the Procharger was the best combo out there. Do you think people will be running turbos? Also not everyone has unlimited funds when it comes to heads. You don't need all this special heads to make power with turbos. I would love to have the warp 6 heads on my combo but I don't have unlimited funds. Big Chief and Butler are well over 2800 hp with eheads. It cannot be that bad but I know u can do better with better heads? Thanks.

I could make more hp with better heads just like a turbo would those 481x turbo engines don’t have e-heads on them, there’s a reason!
It’s pretty simple the better flowing head the more hp NA or PA!

I respect your combo as u r going round after round with it. If it makes u happy and not breaking anything. That is the best combo especially if ur not setting the world on fire. U only need urself to be happy at the end of the day. Daddy Dave was breaking his Procharger every time he race before. U dont see turbo guys burning up their turbo on a pass do you? I'm sure Daddy Dave knows more than what hes telling us on the show.

I’m just repeated what he (daddy Dave) said if he had the front end room he would have stayed with a pro charger.


GTO George

I saw that episode too. But he was having issues with the Procharger every time. I'm sure he realized that too! He went from Nitrous to Procharger to turbos. And looked at what Kyle Kelly said. I cant keep up with this twin turbo cars anymore. I'm sure he will convert soon if he wants to be on top!

I wish I have unlimited funds just like them guys! I don't know whats their Day job but I'm sure it is not just coming from that!

I’m not saying that turbos cant make a **** load of power, sometimes it’s better to fine tune a combo before turning up the boost you might be surprised.
As fo Kyle Kelley he might be getting some freebie stuff from Musi!

GTO George

I hear u about fine tuning first. When we are the engine dyno, all I wanted was 1000 hp and that's it. First pull was 1080 at 5200 rpm with 20 plus boost with a 13.4 AFR as my wastegate wasn't bleeding enough boost. I also learned a lot of screwing around with the Blow thru carb based on my dyno experience with the help of my Good Friend Charlie!!! I wanted to turn up the boost on the last pull but I had some header leaks and didn't adjust the home made boost controller to make a difference in boost. I wanted to run 20 psi to see how much power it would have made but it still went to 15 psi on the last pull. My motor was on the dyno for almost a month with 50 plus pulls due to fuel pump issues and waste gate issues.

The smaller ci motors need more psi to make the equivalent power to the larger ci motors. Thats all tom is trying to say.. My 198 ci motor made 750 hp with 35 psi. But theres more to it then that. Like compatibility. Having the right size turbine wheel vs the amount of exhaust gases that will be spinning it to effectively get the most out of the compressor wheel for a given cubic inch .. I started out with a 76mm compressor wheel matted with a 67mm turbine wheel . Then i realized at 35 psi is was
all done . All it did after 35 psi was make heat ! Same thing these blowers are known for. So basically after that, went with a smaller commpressor wheel of 68mm and a larger turbine wheel 70mm . Now i was able to make more power with a smaller turbo on the same motor. The biggest concern i see with this blower on the street is keeping the heat out of the intake. If you can do that you will be able to keep it togther with AFR and timing . So E85 will be a good idea as long as you can keep the heat out. If you cant, the e85 will not be enough and it will detonate..11to1 with a blower sounds like a stretch to me.. An intercooled turbo setup ive seen it done..

Wasting your breath Charlie, Can't help someone who knows it all.

Tom V.

ps Back on pistons and head gaskets.
Put the right pistons in your engine, sir, and run 9.0-9.2 compression ratio on the E-85 fuel
and you will be happy and the engine will give you a lot of enjoyment at lower boost levels..

Thats also true with root blower engines. The smaller then engine the more boost you need to make up the difference in the cubes BUT without the rest of the parts to go along with more boost it won't be a happy engine.
What tom was trying to say was mumble jumble but it was getting late for him. lol!


GTO George

Performer needs to run carbs (2 dominators) on his blower it would take care of the heat he might have in his entake or even blower that way the e-85 will cool everything! If he doesnt match the exhaust side.......headers........exhust pipes.....etc it won't matter any ways. Remember what you put in you need to get out....pretty simple.


GTO George

I never thought of it that way . Adding another carb to help with the intake cooling. Interesting..

I was wondering , has anyone ever tried putting a hat on a roots blowers carb with a intercooler and conected to it to see if it could draw through it ? If it could run maybe it would help it cool the air charge? lol.. If i had one id try it just to see... I would imagine that when those blades get spinning it would create a heck of a draw ..

Don't need an intercooler with e-85.


GTO George

I decided to remove my comments to George vs screw up this mans thread.

Tom V

Tom, I’m sorry that you’re getting confused but you’re wrong on my info. There is only time one of my engines made 20 lbs of boost and it was on a Dyno...it has a smaller camshaft, less flowing heads and smaller tube headers. That was a long time ago that engine broke it had an IA block. This is a different engine, I’ve had this engine quite a while it has a better camshaft, better flowing heads and bigger tube zoomie headers, that all adds up to a better flowing engine and a lot less boost.... but on a plus side more HP!


GTO George

Thanks for the new information George. So what was the HP number on the dyno when you were at 20 psi of boost George? The engine was telling you something, but happy that you finally figured it out.

Tom V.

It’s a secret if I told you............
It’s been posted before!
This engine I have now has never been on the Dyno only the dragstrip but it doesn’t have to be the ET speaks for themselves!


GTO Geirge

arguing or not theres been plenty of good info on both sides....lol been good reading

how awesome would it sound @ 15.x cr on the street even tho i guess i could get the same with lower cr and more boost.


i was planning on the bug catcher but ive also been lookin at the fast xfi dual efi blower setups they have and theres also an efi blower spacer with injectors to use whatever tb's a person might want. but if maybee carbs would be better.

You may also think about aluminum rods, I have GRP’s in my opinion I wouldn’t run a supercharger without them also use Brad Penn oil it’s a must when using alcohol as fuel.

GTO George

tom v.

if a gasket 4 times as thick would get me to 8.9ish which like u said probally wouldnt stay. what about 1 half as thick? wouldnt that get it closer to the 10 range which might survive the 6 psi and e85?

I'm glad u did not take it the wrong way. It is a lot of good info if u didn't think of negative on the posts. Good luck with your build.