View Full Version : street motor compression
bought street motor from bowers 632 c.i. was suppose to have 10.5 compression it has 11.3 is this to much for street?
lotsof454sss
06-05-2007, 10:49 AM
I just have to ask....Did you read all the post here before you bought your engine??
some are my posts bought engine way before posts just got it a couple of weeks ago
bjuice
06-05-2007, 11:25 AM
to answer your question...NO...its not too much for a naturally aspirated street engine...you want to make sure you keep good gas in the motor...the Amoco 93 octane white gas is good stuff...11 to 1 compression is about the highest you would want to go on pump gas street motor ( my opinion).....do not SLIP and put some cheap gas in that motor cause its right there on the border...
i do not know if you have access to racing gas at the pump..
here in my home town they have leaded racing gas 110 ast the pump at some stations....it would not be a bad idea to run a couple of gallons of 110 with every 10 gallons of 93 octane...
i mean look....you need some compression to make some decent HP....I DO NOT think you would have appreciated that 632ci motor if it were a 9.5 compression motor..it would have been a slug...( my opinion again)
not taking up for bowers just telling you how it goes...compression makes HP.......understanding there is a limit to what a street motor needs to be.
i have had more than one 11 to1 compression street motors..as a matter of fact i had some of the fastest 406ci street pump gas 11 to 1 motors in town at one time..
just curious...how or who did you have figure the compression when you got it back from bowers ?
Brian
sp2816
06-05-2007, 11:31 AM
zano wrote:bought street motor from bowers 632 c.i. was suppose to have 10.5 compression it has 11.3 is this to much for street?
Other factors come into play, such as the camshaft timing and fuel that you are planning on running. But, IMHO for "street" driving and 93 octane fuel, I would say that it is too much compression.
As I calculate, the overall chamber volume needs to decrease by about 10cc's to get to 10.5:1 and 18cc's to get to 10:1.
Bill M
bowers just sent me the cam card dyno and compression ratio yesterday it was suppose to be 10.5 he said its 11.3 ross flat top pistons comp can 785 766 gross lift 278 290 duration at .05 also seems like alot of cam for the street dynoed 945 at 6000 rpm comp cam says it will not idle good bowers says on dyno it idled at 850 real nice also said flat top pistons burn better and alum. heads them 2 things make it so you can get away with 11.3 comp. i hope he is right what do you think no racing gas around here but 94 octane sunoco
mcracecars
06-05-2007, 12:56 PM
I would have a difficult time beleiving the engine has or is anything he says it is.
It is probably a big block of some kind.... check it out...
woodsman
06-05-2007, 01:14 PM
zano he has never told the truth before why would he start now just my 2 cents. Wesley
bjuice
06-05-2007, 02:11 PM
ZANO- have you run the motor ? and if so what have you used as fuel ? or what was the fuel used on the dyno ?
also street use means different things to different people...to me street use means driving it to a local cruise inn on a Saturday..
for some it means driving it back and forth every day to work and 500 miles one way to a vacation spot.
Brian
it sounds like nobody really knows and your right i think this is what i got. i do know its a merlin III block victor heads ported intake i hope the rest is right. i should have the car back together in a month or less i'll let you know
over and out zane
bjuice
06-05-2007, 02:39 PM
Mix your 93 pump gas with some 110 and go enjoy your car on the street...my goodness a 11 to 3 compression motor is nothing like these 14/15/16 to 1 compression beast out here racing on the strip...
the type of fuel at this level is very debateable..I HAVE PERSONALLY RUN 93 OCTANE AT 11 TO 1 and hurt nothing.......
i will almost guarantee you that at 11 to 3 compression this will make you a hot little street motor...just mix the gas to be safe on any detonation..
your orginal question was " is 11 to 3 compression too much for street"
now if ya building something to drive to work everyday then NO..but for a weekend warrior car..GO for it...
i will bet the 632 would have never made the HP you posted if the compression was 9/10 to 1...
...and like Bill said unless you know the exact cc's of the heads, deck height, thickness of head gasket etc... you will not know what the compression is..just beacuse the pistons say its a 11 to3 compression pistons doesn't make it that compression unless all the above are working hand in hand.....
Brian
edvancedengines
06-05-2007, 02:44 PM
Not my idea of a driving on the street engine, but it would be fun to play with. That camshaft is humongous for a street engine. It for sure should be bleeding down most of that low rpm cylinder pressure.
I don't doubt that he could get it to idle at 850 rpm. I can get just about any engine no matter how radical it is to idle at a lower rpm, usually 700 - 750 Rpm, and I actually do it to adjsust idle air/fuel, then I idle them to where I want them to be. . That does not mean it will have any power below 10,00 rpm though. I am exgarrating.
He is right about the flat tops usually having a more complete burn than a mountain dome. (My words). I am just wondering how in the world with flat top pistons and an Edlebrock Head it will have 11.40 - 1 compression? How big are your combustion chambers? How thick is the head gasket? and How deep in the hole are the pistons, I.E. Deck ht. ?
Ed
bjuice
06-05-2007, 02:51 PM
Ed- i had the same thoughts and questions also onthe cc's ,deck height. gaskets etc......i just pulled up Shafiorffs pump gas 632 motors and posted the spec's...looks like they are bringing their motors in at 10.75 to 1......
again i am speaking of cruise inn, Saturday night Speacials.....
Below is the specs on Shafiroffs 632 ULTRA STREET
Horsepower 900 @ 6200 RPM
Torque 845 @ 4600 RPM
Bore & Stroke 4.600 x 4.750
Comp Ratio 10.75 - 1
Block Blueprinted Dart Big "M" 10.2" Tall Deck w/4 Bolt Splayed Caps
Heads SSRE/CFE 385cc Fully CNC Ported Aluminum
Valves 2.300/1.880 Severe Duty Stainless Steel
Crank Callies 4340 Magnum Pro Series
Rods Lunati Pro Mod 6.660" w/220,000 PSI Bolts /
Crower Big Block Sportsman
Pistons JE/SSRE Custom 10.75 - 1 Aluminum
Camshaft Comp Cams Custom "Street Roller"
Lifters Comp Cams Solid Roller
Timing Set Cloyes Tru Roller w/Torrington Bearing
Rocker Arms Crane Gold Series Aluminum Roller Rockers
Intake Manifold New Merlin "X" 10.2 Dominator
Valve Covers Polished Cast Aluminum w/Logo
Oil Pan Moroso/SSRE Pro Windage Series
Dyno Yes. Actual Dyno Sheet Provide
woodsman
06-05-2007, 03:06 PM
Brian I went to Wallace racing web site and run the figures that you gave from Scotts 632 and only came up with 11.22 horsepower gain on old to new compression so I think you are right about running some good strong gas. Wesley
i looked at shafiroff engines thats why 11.3 to 1 scares me shafiroff does not do it on steet engines my intake is a edelbrock it was suppose to be a merlin x changed so it had lower rpm hp and it worked mines 945 at 6000 also heads are 118 cc when i get the piston numbers i'm going to call ross and find out exactly what compression this thing has i already have the head gasket type later zano
bjuice
06-06-2007, 04:44 AM
Brian I went to Wallace racing web site and run the figures that you gave from Scotts 632 and only came up with 11.22 horsepower gain on old to new compression so I think you are right about running some good strong gas. Wesley
wes i just copied and pasted Shafiorffs info..i cannot say where its right or wrong..but its what they advertise...go to ScottShafiorff racing and pull up their 632 ultra street motors and you will see more info than what i copied and pasted..i am sure there was something you missed in the calculations cause SSRE is pretty dead on their numbers...i have heard about other problems but i would bet Big MONEY their advertisment on their 632's are dead on....
ohh yeah..i will check this weekend on the master cylinder for you...do not buy one yet...the other guy just let me know he couldn't use it..so i will do ya real good....its at my chassis shop guy's place..
later brian
bjuice
06-06-2007, 05:11 AM
i looked at shafiroff engines thats why 11.3 to 1 scares me shafiroff does not do it on steet engines my intake is a edelbrock it was suppose to be a merlin x changed so it had lower rpm hp and it worked mines 945 at 6000 also heads are 118 cc when i get the piston numbers i'm going to call ross and find out exactly what compression this thing has i already have the head gasket type later zano
Zano:
SSRE runs their ultra streets at 10.75 to 1 on pump gas only (93 octane).if they mixed their fules they could run a whole heck lot more compression on the street ( street engine)..call them yourself and ask them...
i am telling you without a doubt that you can run your car on the street at 11.3 compression....Mix your fuel 93 and 110...or get some 100 street blaze or something comparable...i have a drum of 104 unleaded octane Sunoco oxgentated fuel in my shop..its yours for $300.00...come and get it...your 632 will love it..it sells for much more than that....
This thread has taken a sharp 90 degree turn...your question was it too much compression for the street...the answer is 'NO' if your doing some weekend warrior stuff.......i have a 67 camaro with a 511 bbc...it has 14 to 1 compression...me and my wife drive it to the local cruise inn's and hamburger joints....i run 112 Sunco blue ( Supreme)....i also took it to the track and ran a 6.07 at 115 mph over a month ago...would i drive this car 200 miles one way..NO..but i will drive it locally all around town and BUST anything that gets in my way...LOL......or capbale of it anyhow...
see the car in the show off section
i am not trying to convince you either way....but i have ran some 11 to 1 Hot" street cars since i was in high school...and never re-greted it...we used pump gas back then and never hurt anything..didn't know any better..i would say Mix it today because stuff has gotten so high to replace....11 to 1 is on the high border side of being too much for opump gas but NOT too much for the street.."weekend warrior stuff"...
whats spending the extra $20.00 at the oump when your filing up?..speacially if your just catting around town on the weekends and screwing with rice burners....the extra $20.00 is worth the smell if anything.
besides what ya gonna do if it checks out to be a 11.3 compression motor ?..tear it back down and spend big money just to be able to pay $3.50 a gallon for pump gas ???...if i were you i would mix the gas and leave it alone and enjoy driving the car......just my opinion...
let us know what Ross says.....
Good luck and enjoy..
Brian
brian your absolutely right i don't know why i worry about every little thing thats a great idea to mix fuels i'll let you know how i make out the willys should be together in less them a month thanks again zano
edvancedengines
06-06-2007, 07:43 AM
Zano,
I have figured every possible configuration of engine dimensions I can figure for a flat top piston 632 cu in with 118 cc cylinder heads, and I just can not come up with the compression you have been told that you have. This is assuming that the heads are at 118cc and the chambers have not been opened up. If they have been opened up the compression would be even less.
I still say that cam is absolutely assanine for driving on the street. It will do tons of help for letting you drive with a high compression engine on the street, but I don't think that you have the compression ratio you were told.
Comp is wrong about it idling but I think it will be very sluggish if your tires are hooked up at all low and mid rpm ranges. In my opinion, about what horsepower yoour engine builder is claiming with it, WHO CARES. How much usable torque and horsepower will it have in the rpm ranges where you will be mostly using it. IF it made the horsepower on his dyno he told you, which to me is doubtful using the Edlebrock heads with a lower compression engine, BUT if it did, Are you going to be driving it all the time at maximum horsepower rpm? Didn't think so.
I do not trash talk other engine builders and we all do things differently, but if he was fully understanding that you will be driving this on the street and wanted to use pump gas, he is an idiot. Man that is more cam than most race cars only run. That is more cam than all except the more elite race cars ran years ago. I see a much bigger negative issue with your cam selection than I do your reported compression ratio, which I highly doubt.
The comparison between what you possibly have and a SS street engine using BMF heads is a far different world. I am certain that SS Racing could have put more compression into it but did not bcuase they have no idea about how it would be used and abused by buyers.
I have always had engines with higher compression than most in my street cars before I went to stock junk cars. I do have customers that are driving 11-00 compression SB ' s with cast heads, So it can be done. I have a customer in KC that uses his 11.30 - comprseeion car all the time but it does have EFI so that helps him a lot. It only gets race gas when he is getting ready to race it.
Willys! ?
That is some good news added in here for you. I love all of the old Willys of any year. Most of those are built fairly light too, so the good news parts of this are that with a lighter car you can get away with more compression on the street. With a lighter car you can also get away with a bigger camshat on the street. Just not that big.
Is there any chance you could post pics of your car? Or a link to a pic storage album, or email me pics. I do love those cars.
Ed
ed i just called bowers said how did you get 11.3 to 1 with a flat top piston and 118 cc chamber he said they done work on heads opened it up to 124cc and then something about swept volume and because of the size of bore to stroke its easy. also willys is off frame give me your email i'll send you pictures of frame with motor on and body on rack just starting to put together thanks zane
woodsman
06-06-2007, 12:38 PM
Brian I went and tried it again an came up with the same thing. I just took the 900 hp that Scott's 632" has at 10.75.1 and the 945hp that Zane has at 11.3.1 and still come up with 11.22 hp gain. So I am going to stick with what I know the starter botton on the dash.lol. Wesley
sp2816
06-06-2007, 12:47 PM
It is just like Ed said, the numbers don't match up and it shows that Bowers is using different math than the rest of us. You can't have 11:1 compression with the flat tops (-3cc to -6cc for valve reliefs), 124cc chamber, 11.5cc for head gaskets, not even to count the 1 to 2 cc's for the top ring to top of the block. You are closer to 10:1 compression because the total combustion chamber volume is from 140cc's to 145cc's.
The sweep volume ( V ) is the volume of one cylinder in cc’s, which is 1293.8cc’s. The total combustion chamber volume ( C ) is calculated as the head combustion chamber plus the head gasket volume minus the dome volume of the piston (yours will be add the valve relief volume), plus the volume due to deck height and ring land. So, that is roughly a total combustion chamber volume of 140cc’s or 145cc's. The compression is calculated as ( V + C ) / C
(1294+140) / 140 = 10.25 : 1
or
(1294+145)/ 145 = 9.92: 1
I had another shop tell me that they could get the big compression with the flat tops. You can but the head chamber needs to be smaller.
Good luck on the rest of the combination of the engine and the Willys sounds cool.
Bill M
i got to tell you . you guys are smart i just called ross tech line asked if i had there flat top piston gave him bore stroke and cc's of head with out knowing piston # he ask me for that first. what would be compression he said 10.25 i ask if you can get 11.3 out of it with that cc he said absolutely not.what should i do know
just called bowers told him ross pistons said you can't make that compression with a flat top piston. bowers said he will send me the math over and out zano
bjuice
06-06-2007, 02:15 PM
You do Nothing but run the motor...whats happened is you got in the end what you wanted..a lower compression streetable BIG block...i am not as techinal as Ed and Bill but i know what Time it is.....the only thing i see that is in question is how the camshaft is going to perform on the street.
IF I WERE IN YOUR SHOES...i would mix 93 octane with some 104 or 110 gas...so your covered on this compression thing no matter if its 10 to1 or 11.3 to 1,..it will run pretty much all the same on this mixture...what your trying to eliminate or avoid by using a little higher octane gas is detonation..the higher the compression the more octane you will need..
DON'T WORRY !!..put the motor in the car and mix your fuel and see how it runs....if it runs good...then GREAT !!!..you have no worries....if the motor doesn't idle good or doesn't perform as to how you think it should..then come back and start picking these guys Brains...or even use one of them to go back thru it ..worse case...
i have fell victim in the past when i was learning the same as you..i got so caught up in listening to so many diffferent opinions and ideas that i ended up changing stuff..long before i ran the motor...so take my advise and benefit from my loss/mistakes in the past....do the obvious which is protect your motor from the NO #1 unkown and concern..COMPRESSION..using mixed fuel or straight 104 or 110 will safe gard you against detonation and destruction..that is compression vs fuel related....the rest of it is all guess work at this point...put the motor in the car and try it out...You might just have you one hell of a combination in that motor.....and it runs great !!....possible right ?????
if you DO NOT do what i said above...then the only option left is send the motor off to another builder and get about 2,000 or 3,000 in hand and hope they are honest....
just an example; If you sent your motor down here to say PAR or Gene Fulton...and they tore it down and put it right back together..your gonna bust up a few thousand after its put back together with new gaskets and re-checking all the tolerances etc... ...
its almost impossible for anyone to say how your motor will or will not run..there is opinions and good ones but not enouigh for you to go back in at this point.....just protect the motor with good fuel..until you know for sure..
and you also have to keep in mind that Bowers probably knows you are on this forum.people cannot stand him for his piss poor business ethics.....he is probably checking these post himself...so i would not be surprised that when you call him up asking these questions He is screwing with you..knowing its coming right back to this post.....YES BOWERS does know his way around this forum..and i would bet BIG $$$ he is reading this and laughing right now..he has caught Hell ON THIS SITE FOR SOMETIME and he isn't about to give away any secrets.....THINK ABOUT IT.....the one thing you have going for you is that you at least have your motor before he learned you came on this forum....if not i would say you might have some issues...but i would have to say you probably got a motor that he done his best work possible.....now just run it and see....if its a 900 hp motor...TRUST ME YOU WILL KNOW AS SOON AS YOU PRESS THE PETAL...THERE IS NO MISTAKING OR GUESSING WHAT A 900HP STREET MOTOR FEELS LIKE....trust me here...
Brian
woodsman
06-06-2007, 02:34 PM
Zane I am like Brian #1 be thankful you got your engine #2 be thankful that it is a BBC (but unable to tell what size). If it where me and I was made of money than I would get it checked out so I could have a clear mind but if not. Than I would do just what Brian said and put it in my hotrod and go have some fun. Wesley
sp2816
06-06-2007, 03:12 PM
That was well said Brian, because you won't know how it will run until you try it.
Bill M
edvancedengines
06-07-2007, 10:01 AM
I agree. Try it and see. If it needs something different it will let you know.
Send pics to
[email protected]
Ed
i finally got paper work went to edelbrock heads are 118cc clean up was .002 felpro head gasket .041 thickness can you figure compression with flat top pistons now thanks zano