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Matthew Samba Member
Joined: January 29, 2004 Posts: 1760 Location: Eastern Tennessee
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Posted: Fri Sep 11, 2009 4:40 pm Post subject: |
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Sigurd wrote: |
I don't think anyone has brought up Chevys. Confused |
This is the part about chevy's
mightymouse wrote: |
You see the hotrod article, they bought the 572 crate motor thats 12.5 to 1, its supposed to run on 110 octane only.
They put it on 91 and knocked out a few degrees timing and it barely lost any HP. Ran fine, didnt run warm and they drove it everywhere. When headed to the track, they set the timing back to where it was found to make highest HP, poured in 110, and hauled ass.
This stuff is old news, but it seems to never reach the aircooled community.
Thus you have guys building HUGE motors with turbo compression, and they think thats a good idea, why because of retards from the past who built these motors wrong.
When will the legacy of stupidity and fear end? i dont know, but im gonna try damn hard to get rid of it myself.
Spread the knowledge. |
_________________ 1965 Beetle sedan
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craigman Samba Member
Joined: March 28, 2004 Posts: 2397 Location: redding
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Posted: Fri Sep 11, 2009 4:53 pm Post subject: |
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I just don't get why people are stuck on low compression motors.
Unless they've been reading the Gene Berg books.. |
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EPETREA Samba Member
Joined: September 07, 2007 Posts: 391 Location: DFW TX
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Posted: Fri Sep 11, 2009 5:27 pm Post subject: |
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I say just screw it and build it just the way you want...nobody on here has any experience with acvw's do they?? run as much compression as you want. Hell if 1 3/4 exhaust is good why not shoot for 2".
Problem is your going to end up with a engine that is made to hum at the top of the rpm range and THAT doesnt always make a street friendly engine. Your low end will suck!! Mid range will be soggy and it will run best at high rpms. Point is, there is nothing wrong with the combo that combo(except mismatched a bit) for the strip, but I dont think you'll be happy with it on the street. When the engine/cam doenst start to come alive untill about 3500-4000, and your shift points are in that range, how well do you think that will work. Design your engine for where you are going to run it. Dont try to make a high end combo fit on the street. And yes,,, you can have tooo much compression on Air cooled's. Without the water surrounding the cyls to provide an even combustion cycle/engine temps you will have more of a problem with detonation while running on street gas. but Like I said,, go ahead and do it. just remember what you were told when you end up rebuilding it again. Just my 2 cents worth.
Buy your best buddy a good tow strap and keep his number close. |
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jeff denham Samba Member
Joined: January 14, 2006 Posts: 780 Location: calif
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Posted: Fri Sep 11, 2009 11:22 pm Post subject: |
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im not agruing with you mighty mouse but have you ever run a 5.7 or a 5.8 on a 82 crank just wondering how that recipe worked for YOU? we all have are different ways of doing things. i like those lengths on my 90 strokes. and 82 i would have chose a POR LENGTH.or VW LENGTH. but hey we all have are different ways what works best for yaul. i personaly believe in the 1.62 to 1.65 ratio have had exelent and winning succsess.enghof rambeling. JD . _________________ www.dprmachine.com |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 12:26 am Post subject: |
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jeff denham wrote: |
im not agruing with you mighty mouse but have you ever run a 5.7 or a 5.8 on a 82 crank just wondering how that recipe worked for YOU? we all have are different ways of doing things. i like those lengths on my 90 strokes. and 82 i would have chose a POR LENGTH.or VW LENGTH. but hey we all have are different ways what works best for yaul. i personaly believe in the 1.62 to 1.65 ratio have had exelent and winning succsess.enghof rambeling. JD . |
IMO thats on the very lowest end of the chart, but i know your no rookie and have done well in this arena so i have respect. I also have done quite well, i just dont have a huge shop or name, always stayed quiet and just won LOL.My thoughts are: a stock 1600 comes with almost 2.0 rod ratio. why go backwards?
If your trying to make some more torque great, but at the expense of alot of parts, to me is not so great. And whens the last time ANYONE here drove a stroker crank bug and had ANY complaint about torque?
I try and shoot for 1.75-2.0 whenever i can. Ive never had a problem with it. but i build each motor to suit the clients needs. very few are alike.
So i cant say i have a recipe down where ive built 100 2332's with 5.8 rods and its magic. i just like to calc the rod ratio and the dynamic compression.
Have to remember how much more load a short rod puts on the cylinder/piston. Id say running 1.6ish rod ratio would be OK if you had small pistons and wanted some torque. But as bore increases your better off moving up on the chart, closer to 2.0 the better.
Jeff being a head guy, you well know that the longer rod makes it easier to fill the cylinder, so not as much runner volume is needed. A guy can make more power with less expensive stuff. No its not some HUGE difference that ive ever seen, just a small part of the equation i had to mention.
The long rod motor is happier to rev, wears parts less, is easier to tune, less likely to detonate. For me its just the way to go. Is it harder to fit in most bugs,a little yeah, does it sound cool at idle and low throttle, YEAH. LOL.
In reality it goes back to what i always say. You ask 10 chefs for a recipe for chocolate chip cookies, youll get 10 totally different recipes. They all are the same thing, they all look the same But damn they sure dont taste the same.
Its the same with engines. especially aircooled. Every builder does it different and as long as you stick with what they say, and it works for them, it will work for you.
But when you look around, you will see the few that win every race, and break all the records. If thats what your after, thats when all this little stuff counts.
Anyways, i could go on for hours. Didnt mean to type a book. Its my fav subject. Later dave.
Oh yeah, ill be calling you soon jeff. have a client whos dying to run a set of your heads. _________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 12:48 am Post subject: |
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Just thinking about it, 5.5 on an 82 crank is cool. 1.70 rod ratio. Thats doable.
1.76 with a 5.7 rod.
*likes thinking* lol
Never built any motor with an 88 or 90 mm crank,( never needed to) but shit itd need a 6 inch+ rod to even be in the realm of sane. _________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Sat Sep 12, 2009 7:51 am Post subject: |
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mightymouse.
Have you ever tried to put a 1.7 or larger (5.7" rod 82mm stroke) rod ratio in a Type 1 case? You are already out of room just by adding the 82mm stroke crank. 2-1 would be great but it just wont fit.
ACVW's run less compression because they have a 100 degree hotter combustion chamber. The detonation point of the gasoline (LEL) is based on temperature. Adding more compression adds more temperature. You want to reasonably be able to predict where the detonation point is and aim for somepoint below that for your ignition to occure. The same gasoline in a water cooled car could use a higher compression ratio.
Just choosing a longer rod does not necessarly help you. You need to look at rod angle also. Short rod ratios are good for certain applications and large are good for others. It depends on your Application and the constraints of the engine you are working with.
About the guys giving the advise. Ive been to some of their shops. They are not fancy NASCAR type shops with lots and lots of equipment. You walk thru some of them and you cant imagine how they could rebuild an engine let alone win races. But they do. They have sucess because of their knowlege and experience. |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 11:57 am Post subject: |
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Jimmy111 wrote: |
mightymouse.
Have you ever tried to put a 1.7 or larger (5.7" rod 82mm stroke) rod ratio in a Type 1 case? You are already out of room just by adding the 82mm stroke crank. 2-1 would be great but it just wont fit.
ACVW's run less compression because they have a 100 degree hotter combustion chamber. The detonation point of the gasoline (LEL) is based on temperature. Adding more compression adds more temperature. You want to reasonably be able to predict where the detonation point is and aim for somepoint below that for your ignition to occure. The same gasoline in a water cooled car could use a higher compression ratio.
Just choosing a longer rod does not necessarly help you. You need to look at rod angle also. Short rod ratios are good for certain applications and large are good for others. It depends on your Application and the constraints of the engine you are working with.
About the guys giving the advise. Ive been to some of their shops. They are not fancy NASCAR type shops with lots and lots of equipment. You walk thru some of them and you cant imagine how they could rebuild an engine let alone win races. But they do. They have sucess because of their knowlege and experience. |
1st paragraph, rod length has nothing to do with the case. it simply makes the engine wider.
2nd paragraph, .....no. compression has to match cam, if you have too much cam, and low compression, you wont even make enough pressure in the cylinder to properly burn the charge, and make even more heat than a stock motor.
3rd paragraph, rod ratio is calc'd so you know your rod angle. too short causes the angle to be extreme and sideloads the piss out of the piston, also causing higher pistons speeds which stresses the rod, crank, and ring stack more.
4th paragraph, I know this one well. I work out of my house dude. if you havent heard of dave's garage, stick around you will. Ive been building aircooled VWs since 1990. broke records, made people stand up and take notice. i stepped out of aircooled racing for a while to pursue another dream.
Im back now, but dont have my own race car again yet, and dont have any big racing accounts for vws. I simply build longevity motors for buses.
_________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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souper Samba Member
Joined: September 26, 2007 Posts: 67
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Posted: Sat Sep 12, 2009 12:47 pm Post subject: |
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mightymouse the longer the rod the more you have to clearance the case at the cyl. base. |
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Bad bug Samba Member
Joined: March 11, 2006 Posts: 1119 Location: Jamaica
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Posted: Sat Sep 12, 2009 1:15 pm Post subject: |
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Sigurd wrote: |
I don't think anyone has brought up Chevys.
Jake doesn't build anything less than 9:1 and he just put 10.2:1 into a Bus and I don't see him ever get questioned... |
Because jake tunes the shit out of everything, collects data like a mad man, analyze and rework his combos to perfection. But seriously yes i do agree that if you are going to build high compression engine running pump gas ( my thoughts, was going to start a thread about this ) chamber design would have to change cam and compression would have compliment this also. Oh god were is jake when you need him. |
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Sigurd Samba Member
Joined: April 18, 2006 Posts: 2639 Location: Rockford, IL
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Posted: Sat Sep 12, 2009 2:14 pm Post subject: |
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I was hoping he'd show up. He's debunked the low compression theory numerous times.
Err, I mean, heavens to Betsy!! 6.7!? Are you nuts?? |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 2:49 pm Post subject: |
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souper wrote: |
mightymouse the longer the rod the more you have to clearance the case at the cyl. base. |
that depends on crank size. _________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Sat Sep 12, 2009 3:09 pm Post subject: |
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So I guess that means no.
Rod length does have issue with case width.
But anyhow, since you are an expert at this, what do you use to plug the holes in the case at the cylinder spigots from clearancing it for the 6" rods? JB weld?
Or perhaps you weld a 1/2" piece of aluminum onto the decks?
Also if your whole point about compression ratio is about static vs dynamic ratios then of course dynamic is always the best.
But if you want to use 11-1 static compression on your street engines, go ahead. We will be seeing you soon in the negitive feed back section. |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 4:04 pm Post subject: |
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Jimmy111 wrote: |
So I guess that means no.
Rod length does have issue with case width.
But anyhow, since you are an expert at this, what do you use to plug the holes in the case at the cylinder spigots from clearancing it for the 6" rods? JB weld?
Or perhaps you weld a 1/2" piece of aluminum onto the decks?
Also if your whole point about compression ratio is about static vs dynamic ratios then of course dynamic is always the best.
But if you want to use 11-1 static compression on your street engines, go ahead. We will be seeing you soon in the negitive feed back section. |
Never ran 6 inch rods Never needed and engine that big.
And since you missed it, i went low 12s with a 1679 for 10 years, beating smart guys like you with ease. It was just under 11 to 1, on pump and it was my only car.
what was that you said again?
youll never see me in the neg feedback section. Ive never lost a motor ever.
on 50 shot my 1679 made just over 200 hp.
The 2165 im doing for dan now will make over 300 hp on jug.
What jimmy is this? i probably know you. hehe. not 2565 jimmy from washington?
Oh yeah, stat and dyn Cr go together with cam choice. You cant pick one without knowing the other, and what altitude your going to run it at. _________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 4:10 pm Post subject: |
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Oh and jimmy, i do get what your saying about where the rod contacts the case with a longer rod. But as i said, ive never built a 2500cc+ motor.
So i havent run into it personally. i dont recommend any crank over 78mm in a vw case. Ill never need it. _________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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Bad bug Samba Member
Joined: March 11, 2006 Posts: 1119 Location: Jamaica
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Posted: Sat Sep 12, 2009 4:30 pm Post subject: |
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Well if you look at the last boxer engine vw did it had a 76mm crank and 94mm pistons ( waterboxer of course ). Rods are 5.4 inch i think. |
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mightymouse Samba Member
Joined: May 26, 2004 Posts: 4220 Location: las vegas
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Posted: Sat Sep 12, 2009 4:37 pm Post subject: |
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Bad bug wrote: |
Well if you look at the last boxer engine vw did it had a 76mm crank and 94mm pistons ( waterboxer of course ). Rods are 5.4 inch i think. |
yeah and thats a killer motor. my 2 favs are 2109 and 2165.
I have overstated the rod length deal in this post trying to prove a point. While i do think 5.7 and 5.8 rods are good on 84/86/88 cranks i didnt mean they need to be on everything. I just hate seeing 2332s with 5.4 and 5.325 rods. stupid shit that is.
Thats all im trying to say. the 2165 ill be doing next will have 5.5s for a 1.79 rod ratio. Its gonna have huge heads and a ton of nitrous sprayed acrossed it, in a street driven car.
So, as you can see im not going to run 5.7's or 5.8's. But if i built a 2443 you can bet i would, and i prob wouldnt use a vw case either.
_________________ Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson
Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters. |
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Bad bug Samba Member
Joined: March 11, 2006 Posts: 1119 Location: Jamaica
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Posted: Sat Sep 12, 2009 5:29 pm Post subject: |
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A 84, 86 or 88 crank with a 5.7 inch rod will make the engine wide, also this will not allow such an engine to fit in the beetle engine bay without cutting. That's why 5.4 or 5.5 inch rods were used with the build up of some 2332cc engines for race application some folks use 5.7 inch rods muffler mike for one uses 5.7 inch rods in his engine. A 2332cc engine with a 5.4 or 5.5 inch rod will be torquey but the rod ratio doesn't look good. You will then have to buy really good pistons with good skirting area to guard against piston slapping in the bores. |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Sun Sep 13, 2009 10:39 am Post subject: |
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A picture says a thousand words.
90 Octane, 7-1 dynamic C/R and 360F head temp.
Link
The flame you see at the top of the piston is the F/A mis igniting before the flame front reaches it. |
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Sigurd Samba Member
Joined: April 18, 2006 Posts: 2639 Location: Rockford, IL
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Posted: Sun Sep 13, 2009 10:44 am Post subject: |
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Video is private. |
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