cams vs. compression

Matt Harris · Post by **Matt Harris** » Wed Jun 06, 2001 3:29 pm

Hi James,

Yeah I know, it's friggin retarded low, but I got that thing running good so I'm going to go with it for another 10,000-15,000 miles at which time the engine will have 30-35,000 miles on it and will be about time to do a valve job and such.

And what you said about what you read in books and how it plays out in real life is very true. I went into building my engine thinking that 6.6 will allow 87 octane and during the summers I can run 92 for extra cooling, but it didn't matter what octane I ran, it ran super hot either way. So I say, to recommend a blanket c/r for all applications is not very good, and cam along with other things MUST and I mean MUST be considered. I really respect highly what John Connelly says because he is educated in engineering and knows his stuff when talking aircooled engines. Jake Raby the same also, he has allot of experience as well with "high" c/r on daily driver engines. This is why I'm going with more c/r when the the engine is out next time.

I'm the type of person that thinks allot about things, and based on discussion here, the forum, and people I know personally that run 8:1 with 290 cams daily and have no problems, I believe that low c/r is not the way to go to get low engine temps, but rather a more balanced look at the engine as a whole. See ya.

------------------
Matt Harris
78 x 90.5
2007cc
1971 Super

[This message has been edited by Matt Harris (edited 06-06-2001).]

Chris · Post by **Chris** » Wed Jun 06, 2001 5:35 pm

"I just got done, downing another fifth of jack....Now I hear the frogs a'yellin down at the river, anyone for a Pabst Blue Ribbon and some frog legs??"

Jake,
Is it true that they taste like chicken, but smell like fish?

Chris Stanford
Montgomery, AL

BTW, AircooledBreeze says Gentleman Jack is better!

danimal · Post by **danimal** » Wed Jun 06, 2001 5:53 pm

>>>OK here's some practical experience with super low compression and my thoughts. Many of you know that I have a 6.6:1 2007cc engine with a 294 degree cam (e-120), 40x37.5 heads, semi hemi cut etc.<<<

matt, i'm running 7.0:1 c.r. on the turbo motor, and it runs incredibly cool for what it is... 42x37.5 stock heads w/relocated spark plug, webcam 119, dellorto 40's, but no semi-hemi cut.

however, i am running that stupid c.b. hideaway exhaust system, which has stock-sized i.d. tubing... definitely a recipe for disaster when it comes to exhaust heat retention in the heads.

so why am i not overheating, with that low c.r. and super-restrictive exhaust?

>>>And from the outset the oil ran a consistent 231 running at 65 mph on a 85 degree day on the 91 freeway in so cal.<<<

matt, how do you accurately define 231 degree oil temps? has the gauge been calibrated?

i'm sure we may have covered this before, but are you pegging the berg dipstick? is it uncomfortable to hold a stock dipstick in your hand after shutting off the car?

dan
oceanstreetvideo.com

Darryl · Post by **Darryl** » Wed Jun 06, 2001 6:04 pm

<BLOCKQUOTE>quote:<HR>Originally posted by danimal:
>>>
matt, i'm running 7.0:1 c.r. on the turbo motor, and it runs incredibly cool for what it is... 42x37.5 stock heads w/relocated spark plug, webcam 119, dellorto 40's, but no semi-hemi cut.

however, i am running that stupid c.b. hideaway exhaust system, which has stock-sized i.d. tubing... definitely a recipe for disaster when it comes to exhaust heat retention in the heads.

dan
oceanstreetvideo.com<HR></BLOCKQUOTE>

Dan,

I am running the same WEB 119 in my Blown 1776cc also w/ 7.3:1 CR. With 40X37's and mild port from Perf. Tech. My motor loves this combo and it's got one of those "heat producing blowers" on top. I'm only running a 1 5/8" Merge with a stupid Dynoflow or whatever the Tiger ones are.

NO HEAT!! RUNS AWESOME!!

Also Dan, C.B. now has the 1 5/8" Turbo Hidden header for your spooler.

danimal · Post by **danimal** » Wed Jun 06, 2001 6:16 pm

>>>Also Dan, C.B. now has the 1 5/8" Turbo Hidden header for your spooler.<<<

thanks for the info, darryl... i'll check out that header system, but the last time i talked to 'em, they only ever had one size... that was claimed to be 1 1/2", which of course is the o.d. of the pipe... the actual i.d. is closer to 1 3/8".

dan
oceanstreetvideo.com

Darryl · Post by **Darryl** » Wed Jun 06, 2001 7:16 pm

Bad62Bug just recieved his CB Turbo Hider with EFI and it came with the elegid 1 5/8" header. He states that it's a lil tougher than the 1.5" header was, to squeeze in.

He has a trick removeable apron that helps a lot. Looks stock with no visible fasteners.

Check Bad's profile to view his pics.

[This message has been edited by Darryl (edited 06-06-2001).]

Tate · Post by **Tate** » Wed Jun 06, 2001 8:16 pm

Dan and Darryl, you are comparing turbo to normally aspirated? Isn't that apples to oranges? I think if Matt was running a turbo and corresponding cam with 6.6cr he would be right on and probably would run cooler. I just don't see your logic in comparing your combination to his, wouldn't your dynamic compression be higher since your turbo is forcing more mixture into the chamber with the turbo? I think Matt's motor proves the point that these motors like his are not impossible to tune, just very difficult, especially if it gave Art such a hard time.

Darryl · Post by **Darryl** » Wed Jun 06, 2001 8:32 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Tate:
Dan and Darryl, you are comparing turbo to normally aspirated? Isn't that apples to oranges? I think if Matt was running a turbo and corresponding cam with 6.6cr he would be right on and probably would run cooler. I just don't see your logic in comparing your combination to his, wouldn't your dynamic compression be higher since your turbo is forcing more mixture into the chamber with the turbo? I think Matt's motor proves the point that these motors like his are not impossible to tune, just very difficult, especially if it gave Art such a hard time. <HR></BLOCKQUOTE>

AGAIN I AM CONFUSED WITH BEING DAN"S COHORT!

I simply replied to Dan..I am in no way responding to this topic of goofy math.

If you must know, I ran a 1776cc with V6-PTech heads 40X37 w/ Dual 40mm Dells WEB 119 and 7:1 CR. Ignition consisted of, MSD Billet distributer, coil and 6AL with a 5200 rev limit. This was all sent through a Berg 1 5/8" and Flowmaster 2 chamber 2.25".
Ran cool, fast and reliable. Very clean inside when inspected and plugs were always light brown.

The car wasn't driven lightly as I felt I had something to prove to every damn car I saw!! LOL

[This message has been edited by Darryl (edited 06-06-2001).]

bad62bug · Post by **bad62bug** » Wed Jun 06, 2001 8:36 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Tate:
Dan and Darryl, you are comparing turbo to normally aspirated? Isn't that apples to oranges? I think if Matt was running a turbo and corresponding cam with 6.6cr he would be right on and probably would run cooler. I just don't see your logic in comparing your combination to his, wouldn't your dynamic compression be higher since your turbo is forcing more mixture into the chamber with the turbo? I think Matt's motor proves the point that these motors like his are not impossible to tune, just very difficult, especially if it gave Art such a hard time. <HR></BLOCKQUOTE>

I had no problems with mine when it was NA and it ran cool, good berg heads and berg 42s
Ran smooth as silk and had fair power 14.6 in the 1/4
more pics http://hometown.aol.com/bad62turbobug/turbobugpage.html

[This message has been edited by bad62bug (edited 06-06-2001).]

danimal · Post by **danimal** » Wed Jun 06, 2001 8:56 pm

>>>if Matt was running a turbo and corresponding cam with 6.6cr he would be right on and probably would run cooler. I just don't see your logic in comparing your combination to his, wouldn't your dynamic compression be higher since your turbo is forcing more mixture into the chamber with the turbo?<<<

yes, the dynamic compression would be higher for a lot of the normal highway use; where he would be pulling vacuum, we might be at zero or very low boost when cruising.

as a kneejerk reaction, i don't see a small amount of boost/higher dynamic c.r. as an engine cooling situation... i'm thinking the opposite... no doubt, tho, someone will try and correct me

and i'll have to rethink the situation.

with regards to the webcam 119, it's rated at .422 lift, and 240 degrees duration at .050.

i hear what they are saying about it being harder to tune; what i'm really asking about is the facts regarding his overheating situation.

mostly i'm asking because with my 6.6:1, stock carbed/cammed bus motor, i didn't have overheating problems, except for the time that the points fried in gila bend.

i'm not doubting matt, but i'd like to hear about something besides worthless gauge readings.

for those of you that don't follow me, i've been on the vw net since the mid '80's... outside of gene berg, i've only heard of one person who actually tested his temp gauge at the boiling point of water... it was off by something like 20 degrees.

anybody on this list done any calibration testing of oil temp gauges??

dan
oceanstreetvideo.com

James2 · Post by **James2** » Wed Jun 06, 2001 9:23 pm

matt, i'm running 7.0:1 c.r. on the turbo motor, and it runs incredibly cool for what it is... 42x37.5 stock heads w/relocated spark plug, webcam 119, dellorto 40's, but no semi-hemi cut.

however, i am running that stupid c.b. hideaway exhaust system, which has stock-sized i.d. tubing... definitely a recipe for disaster when it comes to exhaust heat retention in the heads.

so why am i not overheating, with that low c.r. and super-restrictive exhaust?
******************************************

Dan your running both a smaller cam and a turbo, which both increase the static compression Ratio! Your just proving John's point.

Hell, I ran 7.3 and a Engle 110 and the motor ran cool also.

Matt was running a engle 120 and 6.6-1. Big difference, he has a bigger cam and less CR.

But like I said before, all this talk about static vs dynamic, VE and such is really not important.

Look at all the people running 8-1 plus on the street and not having problems.

I'm running a power pully and 7.7-1 with a engle 110 in a full body sedan, and it was 95 here to day.

Of course this happens in Georgia, near sea level.

I'm building a 2275 with dual 45 dells and a web 109. It will run 8.8-1 CR.

Tate · Post by **Tate** » Wed Jun 06, 2001 9:37 pm

Sorry Darryl, didn't mean to lump you and Dan into a single entity. Thanks for the replies, and I have a question for Matt; what temeratures do you run now that your motor is jetted correctly? I like these more civilized discussions, much more useful for information gathering. I hope it stays this way!

Darryl · Post by **Darryl** » Wed Jun 06, 2001 9:55 pm

<BLOCKQUOTE>quote:<HR>Originally posted by Tate:
Sorry Darryl, didn't mean to lump you and Dan into a single entity. Thanks for the replies, and I have a question for Matt; what temeratures do you run now that your motor is jetted correctly? I like these more civilized discussions, much more useful for information gathering. I hope it stays this way!<HR></BLOCKQUOTE>

No hard feelings. Just had to clearify.

Post by **Tom Notch** » Wed Jun 06, 2001 10:04 pm

I have done plant automation (Big ships, boilers, 47k shp diesels, etc) work for years, now its on commercial jets like what you fly in. Calibrating gauges has been a routine of mine for over 20 years. but maybe I'm l#$^g to you again, dan,

.
Gauges are not that bad and are really easy to check. So my answer is yes, my reading reveal the truth.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Wed Jun 06, 2001 10:13 pm

I test alot of gauges with the boiling water trick, cylinder head, oil temp and etc...

I have never found any that were more than 8-10 degrees off....Gauges are rather accurate, but the senders are the problem, if there ever is one..