Too much compression for boost?
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- เผยแพร่เมื่อ 5 ต.ค. 2024
- Is this too much compression? Dome top pistons, with boost? Will it work?? We gonna find out!
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Need longer videos man. You’re one of my favorite channels to watch
I appreciate that!
11.5:1 is zero problem on alcohol, we run 12-13:1 on roots blown big block stuff with 40+ psi of boost no worries. X275 guys in the 14:1 range. You’ll be safe and sweet mate.
What about 11:1 on e85?
@@nalley6815 no problem depending on combination and engine platform, tuning window narrows somewhat but have done 11-11.5:1 successfully boosted on E85 on a few engine platforms.
@@chrispalfreyman8434 this is gonna sound childish as hell so prepare yourself. I’m trying to make about 1150-1250 to the tire. The only reason I’m looking at 11:1 is because John Doc has an LS swapped twin turbo mustang running 11:1 and it just sounds insane lol. Not like most boosted LS’s running 9.5:1 that sound like a damn stock Chevy 1500 with an exhaust. I know that’s the dumbest sounding thing somebody could say but that’s just how I feel about it….. So I was looking at building something a little higher compression but not if it meant I was boost limited. Not worried about pushing timing so that doesn’t bother me
@@nalley6815 I've tuned a 6.0 LS, fairly healthy hydraulic roller, 11.5:1 comp, cast 80mm turbo. Was a class limited deal, from memory it made 1100whp on E85 non intercooled and around 23-25lb boost. You should have no issues doing what you are chasing.......but you will need a good tuner.
@@chrispalfreyman8434 wow no intercooler on that deal? You’d think with the higher compression it would need it. Do you think it would be fine to drive on pump 93? Be kinda nice to have a dual fuel setup for drag and drives. Be expensive though I bet
I take out an engine once every few years and it feels like I'm doing it too often yet here's John pulling one out every week like it's no big deal. This man is dedicated and it's what makes his videos so great.
Compression will be fine. But it would be great if you had some flat tops with the chambers softened on the heads.
💯 flattops at .000. No, in the hole! Over .045 hot with gasket flat deck and a wedge. I think you may have found what is blowing it up. Any excess deck will detonate. Trust me!
@@Bbbbad724 Yes. Do you think it traps unburnt fuel towards the far end of the cylinder with a dome piston?
@@dondotterer24 Yes it does, and during detonation it is like a nuclear reactor meltdown, flame going everywhere and lifting the heads , if you have cylinders side by side you can blow liquid fuel from the detonating cylinder into the one at under mid stroke and it will get a double blast one hard run that lifts the heads with the piston in that far even with aluminum rods is going to hurt it bad. Wedge heads can’t take that.
@@Bbbbad724 Wow. Great information. I never thought it through that far. Most people don't know when it's going into detonation especially with turbos. Thanks
@@dondotterer24 Detonation is caused by excessive back clearance or the squish area being more than .045 from the piston crown, if you have rods shrinking and growing and you already have a gasket as thick as the squish should be and some cylinders are.030 below deck with methanol it will be like a calliope lifting the heads and flexing the heads up and down. I think the problem primarily is heating and cooling the pistons and rods and detonating moving around, if liquid fuel is swapping cylinders and having uncontrollable pressure waves it is eventually going to give up. I would get it to zero deck and I would get the information on the rods on expansion time and rate along with the elasticity of the rod growth. Also , knock sensors especially where a cylinder side by side like 5-7 or 7-8 on a Ford. I am thinking that it is lifting the heads. You want the squish and pistons to nearly collide, and if the CR is too high put a dish in them. I used a slow motion camera during a dyno pull on a methanol engine and methanol burns so clear it took a slow motion video to see that it was lifting the heads just enough to blow fuel into adjoining cylinders. It was chaos.
It's not overlap that lowers the dynamic compression is the intake valve closing time. That's the last thing that happens before compression. Regardless of overlap a cam with 40⁰ int closing will make higher compression than one with 50⁰ int closing (in the came motor obviously)
The thick squish area is going to take some away but the compression is well within range. Should give you a pretty decent tuning window
you're supposed to check compression height at the wrist pin not on the top of the Piston towards the intake or the bottom of the Piston towards the exhaust, because that's where the Piston rocks on the PIN. good luck I like your videos
Here to learn about compression. Planning 9:1 on an M50 with pump gas (92) with about 20 pounds of boost but would love to hear that I can tune for higher compression safely or understand how to determine how compression impacts detonation and tune on purpose rather than with bro sciene.
We use standard volume high pressure Melling Billet oil pumps in the turbo engines. I like using a copper gasket between the pump and the main cap too. I feel like the copper gasket helps absorb harmonics to keep the cast iron pumps from cracking and the pick ups from falling off and breaking
Those are nice pumps, I want to try one at some point! Good point on the gasket too, never thought of it like that. Hope to see y’all soon!
I think you’d be happier with a flat top closer to the deck than a dome that far down. You could find some different pistons with a larger compression height. You have no quench with those pistons which will make it more susceptible to detonation when you could have more compression in a safer way. Just my 2 cents.
We run 12.5-13.00:1 on methanol 14-71 blower 30-35psi boost, BBC it’s never caused us a problem fwiw
I am just an old man that blew a chunk of $$$ on my hot rod and my "street car" spins up to 9500 is the limiter and I use LAT 70w my compression is 11.29 on the build sheer at 110 lsa I have 70lbs pressure and up to 120lbs spinning past 6500 rpm so I think Jon is doing rite or what he has been advised to 👌👌👌
Or try the M155HV which is the 3/4" pickup version of yours. I have one of these and my idle pressure is at 70#. And maybe fill that gouge in the pan rail with weld or jb weld....lol.
That too much compression for boost is an old wives tail. Car I helped out on in my teens to early 20s was 13-14:1 and 46lbs of boost on a blown 427 big block
Runnin on 87 octane with factory plugs and ignition system 🤣🤣 just kiddin. You know what youre talking about, far more than I do. Enjoy your content!
Hey Nick!
WOW, that is insane......
Do me a favor and put a oil heater on your pan. Cold oil cant pump and dosnt lubricate the engine well atall. Hot oil and cool coolant is a awesome power package and helps parts live.
Yes, it has one. I gotta do better at using it.
youll be fine will rev up crisper and will spool much faster . of course tuning window will shrink some but you have been great at tuning
Don’t let anyone find out how good low boost high as f comp is 😎💪🏽
Seriously love rolling around with 7psi non intercooled pumping through a second hand vortech v2 diy install, shed built Barra and mashing the guts out of these 30k Subarus and shit builds to make 20+psi engines they are scared to beat up on incase it blows up :) okay boys let’s let the sheep go chase psi numbers, sick video to dude I am really interested in learning about these ls engines to try tinkering on next !!!
I always look forward to your videos! Can't wait to see ya in person winning!! I'll help you carry all that heavy money, cause I'm cool like that!!
✌😂
SBC does NOT need a HV pump. And 60psi is the max you need. And dont use thick gluggy oil, use synthetic. With methanol change it regularly. With avgas maybe twice a year!! Those two points is 40hp. And less heat in the oil as well. Then make certain your oil level is well below the windage tray
He runs Brad Penn green oil. I think thats synthetic?
All the experts say 10 psig per 1000 RPM minimum oil pressure on high rpm high hp race engines. 20/50 oil minimum. some run straight viscosity 40 or 50 weight oil. Brad Penn is a name that comes up regularly. This engine sees over 8000 rpm regularly and has looser bearing clearances than you would run on a street engine. Just an old man thinking out loud.
You would be correct for a healthy street engine that rarely saw over 6500-7000 RPM.
I think what you say would apply to a high performance street engine but I believe a boosted race engine regularly seeing 8000+ RPM needs more than 60 psi to live. Most all engine experts recommend at least 10 psi per 1000 rpm.
More compression should require less boost to make the same power.
Yes correct 👌🏽
Mine is 12/1 compression on a 421 and I run twin 80 /88s I don’t have a problem with building boost at all yours will probably be a beast I’d love to go with a big single turbo idk yet.
What fuel are you on man?
Knoxville is my home track .. if you havent never ben its a hookin track .. no bumps no suprises just a good track .. racing from the backside twards the starting line ??? I have no idea .. ive never done that … otherwise it is a fast track .. if my mind dont change ill come nov 26 n watch !!!
U should use the billet oil pump like billy from SRC uses
I just subscribed to your channel.
Thanks for sharing your build.
Take care, EM.
Just copper coat both sides of the gaskets, let them sit a min or 2 til it gets tacky, then slap them on. No need to spray the heads or block
That's what I'm going to do this time
But the internet says a high volume pump will suck the pan dry! 🤣 Them ole m55hv are better than most give them credit for being
Some SBF guys is swearing on Dish Bish pistons.
Static compression means nothing, dynamic compression means everything. With the right cam that thing is gonna run hard, even with the one cylinder that is slightly deeper in the hole.
You just narrow your tuning window. Less room for error
For a non built Gen III LS what is the recommended maximum compression ratio for forced induction engines ? I'm thinking of using a junkyard LS. A Mustang GT500 M122 supercharger with an adapter or some sort of turbocharger or a pair of turbochargers. Hoping to make around 800HP-900HP with a cylinder head,camshaft, intake, exhaust upgrades.,Thanks for any thoughts or advice.
A boosted Engine on Methanol will be fine with that compression.
Your a funny guy John......
My 347 is 13:1 on 14 lbs. On 112
He runs more than twice that amount of boost but should be ok running methanol.
PLEASE TAKE THE HIGH VOLUME OIL PUMP BACK, AND GET U A HIGH PRESSURE PUMP.
Looking great!!
Overlap doesn’t effect dynamic compression. Intake valve closing is the only valve event relevant.
Your right, I was trying to say cylinder pressure in some of that. lol....the valve events with more overlap allow for less cylinder pressure throughout the compression stroke. Venting some possible usable cylinder pressure to go out the exhaust rather than pushing on the piston. But dynamic compression is the pumping compression that we see when we "pump" the motor when doing compression check. Advancing the cam increases and retarding the cam lessens. But I for sure am not a cam expert, that is beyond my expertise. Well, I'm not an expert at anything on a racecar.......lol
@@TurboJohnRacing yep. All good I enjoy your videos. 👍🏼
11.5 should be fine with methanol. Sure sounds better than 12.9! Do you have any knock sensors on your engine?
Methanol can take advantage of higher compression. The cam timing is everything.
Me personally, i’d cut the domes and use the thinnest gasket possible.
I've always heard 8 to 10 thousands in boosted engines with aluminum rods!!!! I don't think that's too high for boost you'll be fine and have a screamer
I'll be at Knoxville race it's literally ten minutes from my house Knoxville dragway is my home
Nice, see ya there.
How much do aluminum rods grow now?.... use to factor that in to compression
.010 is what I have always heard to use for extra clearance
Yes longer 20 min 30 min please videos
For less than a thousand t shirts
400 Sbc fresh from MPE set up for turbo application
Dart Little M
Callie’s Magnum 3.750
JE Piston 4.155 (4 spares)
Tool Steel Upgrade Wristpins
Wiseco Boostline 6.000 Rod
LJM custom ground cam (Comp Core)
JPP Billet timing set
AFR 235cc Heads ported by CFM
Crower Stainless Shaft Rockers 1.5
Crower offset hippo lifters
Wilson Profiler ported intake
It is what it is
No where near "too much" compression,I know someone that runs waaaaaay more compression than that reliably in a turbo application.
you could have the domes milled off pretty easily to turn them into flat tops......it wouldn't structurally compromise them in any way.
Throw that Pittsburg caliper away.
My pick up fell off when I took off the pan.
Look up how to drill and roll pin the pickup tube to the oil pump.
@@jimandskittum I have replaced it with new melling hv same as his with factory pickup.
@@jimandskittum you can't without a drill press or something its almost a half inch thick
That sucks
@@TurboJohnRacing I liked how you ported intake i just replaced my non high volume for the 55 hv and the top is ported where the bolt goes on top larger than the standard flow
Yes sir!
Why did you not get the m55hv/hp pump
This is the hv55 with the 70psi pink spring.
@@TurboJohnRacing they make a hi pressure hi volume pump also, or used to when I sold parts
💪👍💯
Yooooo
Algorithm.
Shes sweet
Good morning tj another wake me racin vid
No, Our Top Alcohol car numbers.
500ci
55 to 65lbs of boost.
15 to 1 compression.
50 to 60 degrees of timing.
All numbers are ish.
😏
So you’ll be fine.
What stroke?
@@HustlinHorsepower 4.5”
@@HustlinHorsepower small bore, big bore , 4.25
@@fallrookmike - Did you mean to say small bore big stroke?
@@danmyers9372 No, I thought I was replying to @Hustlin Horsepower. I replayed twice. First reply
Boost loves compression.......