:::RHMT::: Real Home Made Turbo
General Category => General Discussion => Topic started by: DmC on April 03, 2009, 12:35:47 AM
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Yeah when vitaras come new in the box they look horrible. They have really sharp edges that could cause some preigniton. Preignition is Detonations bad ass older brother that you don't want to fuck with because he doesn't warn you he just punchs a hole in your block.
But anywho here's a pic of before and after sanding with some 400grit.
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi678.photobucket.com%2Falbums%2Fvv143%2FDmC_01%2FDSC02598.jpg%3Ft%3D1238733576&hash=fb73712dfd2a37e2e8d651b224130b89c5e189de)
Discuss.
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did not know about sharp edges creating pre ignition. oh well, anywho I got my vitara running...its sounds good
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Yeah sharp edges can become hot spots. This is just one of those tricks to use on your way to a 400hp Dseries.
But according to slow crx he already knew how to do that years ago.
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sharp edges create a hot spot, hot spots will ignite fuel prematurely ala preignition.
on a side note ive never seen vitaras with the outer edges of the piston turned down like those, mine we just cast with no finish machining on top.
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Their the FJ distributors brand. I'm not in love with these pistons as they come in the box I'm getting them media blasted and coated Before they get installed
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I resized the pic that thing was way to big.
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ah, well good thing Im not shooting for super high numbers then
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ah, well good thing Im not shooting for super high numbers then
Don't sweat it man about a half hour with some 400grit and they'll look like I have mine I'd say they'll hold up fine without the coating but hey I'm doing it just to see if it really makes a big differance.
Seems to be working great in fowee's car. The guys running 11's on turbo edit. the coating has got to be saving his ass imo.
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mine are stock and dd and havent been sanded worth a tapeworm stringing out of hotrexes ass.
a cast piston that has proven to hold over 400 hp. wht the fuck would you want to mess with a proven formula is beyond me.
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mine are stock and dd and havent been sanded worth a tapeworm stringing out of hotrexes ass.
a cast piston that has proven to hold over 400 hp. wht the fuck would you want to mess with a proven formula is beyond me.
Not messing with a proven formula I'm refining it to perfection. Success is in the details man. I'm going for longevity.
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good tech never seen this prep for vitara's
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good tech never seen this prep for vitara's
+1
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This is some good info, if it is something people are doing to prep there pistons, like for real. I dont know why you would post some shitty info...but...
id move it to another section, and sticky it. or maybe make 1 sticky with "good links" or something.
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When you do it im assuming you just do the face? Like the top of the piston. What im wondering is do you smooth th edge around the outside piston?
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I'm doing the same thing but using this link for a reference : http://theoldone.com/articles/engine_tips/enginebuildingtippistons1.html (http://theoldone.com/articles/engine_tips/enginebuildingtippistons1.html)
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When you do it im assuming you just do the face? Like the top of the piston. What im wondering is do you smooth th edge around the outside piston?
Just the top of the piston only you don't want to sand down the outside edge. on these I did the outside edge only slightly in the valve reliefs ,I had to it came to such a sharp edge that you could cut a rope with it.
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what are you using for coating?
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You can develop hotspots in a 7.5:1 CR engine?
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You can develop hotspots in a 7.5:1 CR engine?
To this I submit the six-bolt 4g63. :noel:
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You can develop hotspots in a 7.5:1 CR engine?
think effective CR
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Think power levels you can get traction.
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You can develop hotspots in a 7.5:1 CR engine?
Think power levels you can get traction.
i don't see the connection between hotspots on pistons installed in low compression engines and traction
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They are can happen in harmony :-X
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You can develop hotspots in a 7.5:1 CR engine?
Think power levels you can get traction.
i don't see the connection between hotspots on pistons installed in low compression engines and traction
How much power do you generate by revving your engine out of gear? Do you have to worry about what octane you use to free rev your 7.5:1 CR engine, or what octane you use to make 450 whp with your 7.5:1 CR engine?
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IMO all you really need to do is go over the piston with a scotch brite pad. Sandpaper is a bit overkill. If you had crap like the old CP pistons, which have uncut releif edges which are prone to getting red-hot, you'll want to grind material.
Hot spots are projections that have lots of surface area but a small contact patch with the base metal. When it can't wick the heat away fast enough, it keeps getting hotter. And by hot we're talking well over 536F, autoignition for gasoline. The piston is dumping heat into the cylinder walls & oil, which are cooled with 200-240F fluids. The arrow & bumples wouldn't get very hot, since it has almost as much contact with the piston as it does with the air.
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If you had crap like the old CP pistons, which have uncut releif edges which are prone to getting red-hot, you'll want to grind material.
All the old pistons were like that, some still are. Although it was a weak spot on all brands of pistons there was a problem with CP's design/materials/etc. But every machinist I've met freaks out about them since they are machined to spec w/ clearance built in so they only have to bore/hone to an exact 81.5, 84, 84.5, etc figure and the piston drops right in. The only reason people like those pistons is because they confuse convenience for quality.
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oh dammit i just got some CP's shit now im fucked or something? i gotta do more prep work?
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Cut the side of the valve reliefs out of them, you'll be right as rain.
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Polishing the tops of the pistons will cut down on heat transfer in and out of the piston. Reduces the effective surface area of the top of the piston. IE-if you zoomed in with a magnifying glass, you'd see the top isn't flat, but more like /\/\/\/\/\/\/\/\. Peaks and valleys.
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JD you mean shave down the Valve relief part that is on the high side of the machine, for isntnace the Round part of the C. Like the old one does.
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You can develop hotspots in a 7.5:1 CR engine?
Think power levels you can get traction.
i don't see the connection between hotspots on pistons installed in low compression engines and traction
It's called load buddy you can't make boost without it. Yeah ive had slipping clutchs save motors before. And it's only 7.5:1 compression at idle you start adding manily amounts of boost into the combustion chamber and your compressing large amounts of air
Compressed gasses make heat, Heat transfers into whatever it's touching thats coolest the knife edge of a piston has alot of surface area being attacked by high temperatures not to mention the sharp edge in the valve reliefs have a small amount of atoms so it takes less energy less time to heat them up.
ever notice how a soldering iron gets hottest at the tip and melt's solder fast then you touch some solder it the side and it won't even melt it.
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The theory is all great and applicable, but therein lies the problem. This isn't a single dimensional question, it's an actual applied real world situation.
How much load does wheelspin induce? There's a turbo is300 twenty feet from me that's been run around for two months on stock injectors because wheelspin doesn't load an engine enough to require cooling from a rich mixture.
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Cut the side of the valve reliefs out of them, you'll be right as rain.
Thanks man
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The theory is all great and applicable, but therein lies the problem. This isn't a single dimensional question, it's an actual applied real world situation.
How much load does wheelspin induce? There's a turbo is300 twenty feet from me that's been run around for two months on stock injectors because wheelspin doesn't load an engine enough to require cooling from a rich mixture.
Thats exactly wy my y8 has been fine for almost a year now with the clutch slipping there isn't enough load to really make the motor do any real work. No load no air mass.
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Wouldnt it be safe to say tho that long 4th 5th gear pulls have similar loads on the combustion chamber such as if you put bigt stickies on that IS?
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Wouldnt it be safe to say tho that long 4th 5th gear pulls have similar loads on the combustion chamber such as if you put bigt stickies on that IS?
Probably not. 2JZ are strange engines, I've been in one that was 14.x:1 AFR at 17 psi and the plugs, piston surfaces, etc, looked great. I don't believe they are any more robust than any other well built engine from any number of automakers but their combustion chambers are very very efficient.
Anyway, what I was getting at is TRACTION. Most of you guys don't have it, and if street tuning the engine is tuned too rich.
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Wouldnt it be safe to say tho that long 4th 5th gear pulls have similar loads on the combustion chamber such as if you put bigt stickies on that IS?
Anyway, what I was getting at is TRACTION. Most of you guys don't have it, and if street tuning the engine is tuned too rich.
Whachoo talkin bout YOseph? I tune like you mom Lean Mean and always ready to hook up.
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this thread is starting to get toooooooo touchy feely.
im fucking bored at work.
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Its snowing as I'm writing these lines WTF? :?:
Nothing to do with the thread, but I'm here so...
Great thread btw ;D
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Lots of snow here too. About a foot last night.
Just had to tell my insurance company that my car isn't modified and will have to write them a letter. :-(
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Anyway, what I was getting at is TRACTION. Most of you guys don't have it, and if street tuning the engine is tuned too rich.
Piston looks good. I didn't see anything about the piston that worried me enough to do this for my build though. As stated I'm sure they'll be covered in a silky layer of carbon in no time anyways; especially if you DD the car.
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I did this to my vitara's today. They were sharp as fuck before. cheers for the tip :noel:
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was going through endyns article section and found this info
http://www.theoldone.com/articles/engine_tips/enginebuildingtippistons1.html (http://www.theoldone.com/articles/engine_tips/enginebuildingtippistons1.html)
same thing the OP posted, just more info on the same thing, really.
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good idea, im gonna make sure to do that this time around so i dont have a repeat of this:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi2.photobucket.com%2Falbums%2Fy5%2Fdingbat17%2FIMG_3687.jpg&hash=962a4ee25ae8d5414e4862d2b647aaeb3a10f60b)
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good idea, im gonna make sure to do that this time around so i dont have a repeat of this:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi2.photobucket.com%2Falbums%2Fy5%2Fdingbat17%2FIMG_3687.jpg&hash=962a4ee25ae8d5414e4862d2b647aaeb3a10f60b)
That looks brand new. Why'd you take the time and effort to pull out such a masterpiece?
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good idea, im gonna make sure to do that this time around so i dont have a repeat of this:
(https://realhomemadeturbo.com/forum/proxy.php?request=http%3A%2F%2Fi2.photobucket.com%2Falbums%2Fy5%2Fdingbat17%2FIMG_3687.jpg&hash=962a4ee25ae8d5414e4862d2b647aaeb3a10f60b)
DO NOT hit a fuel cut revlimit on a turbo D-series. They will melt any piston like this whether stock, Vitara, or forged. That's operator error, sir, and nothing more.
Look into engine management with an ignition cut revlimit, or an MSD Digital box.
The theory is all great and applicable, but therein lies the problem. This isn't a single dimensional question, it's an actual applied real world situation.
How much load does wheelspin induce? There's a turbo is300 twenty feet from me that's been run around for two months on stock injectors because wheelspin doesn't load an engine enough to require cooling from a rich mixture.
tell that to 17lbs spinning all 4 from a stop
Yeah, I guess 200 whp in a 3500lb vehicle might turn the tires over a time or two if you raw dogged it. You didn't tune it based off of first gear wheelspin datalogs, so I dont know why you'd bother to interject that crap? D-series, 10 pounds, would turn your stock WRX out.
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Look into engine management with an ignition cut revlimit, or an MSD Digital box.
i've been using crome's launch control at the strip, you saying its not a great idea? whats out there for honduhs thats ignition cut?
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MSD 6AL with a 2 step
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Look into engine management with an ignition cut revlimit, or an MSD Digital box.
i've been using crome's launch control at the strip, you saying its not a great idea? whats out there for honduhs thats ignition cut?
I've not had a problem with the launch control, but I've a couple friends who've melted pistons like that by bouncing off the revlimiter. I think it's the difference between being loaded and being unloaded.
MSD 6AL with a 2 step
Those are crap. There's a reason why I specifically stated one of the MSD Digital boxes.
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ok. How about with a soft touch?
My DIS-4 HO took a big 'ol shit on me, so I'm not sold on the reliability of the digital shit Put the old trusty 6A and plug wires on, and all is good again.
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Look into engine management with an ignition cut revlimit, or an MSD Digital box.
i've been using crome's launch control at the strip, you saying its not a great idea? whats out there for honduhs thats ignition cut?
I've not had a problem with the launch control, but I've a couple friends who've melted pistons like that by bouncing off the revlimiter. I think it's the difference between being loaded and being unloaded.
i never hit the rev limiter in gear on purpose. every once in a while i'll be looking in the mirror at the car catching me and the cel shift light wont' work right and ill hit it for a split second, but nothing extended.
i've been using the launch control for about a month, id say 30 runs and haven't had any problems.
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ok. How about with a soft touch?
My DIS-4 HO took a big 'ol shit on me, so I'm not sold on the reliability of the digital shit Put the old trusty 6A and plug wires on, and all is good again.
That's nice. Did you ask after your warranty?
The analog boxes do absolutely nothing when they work correctly, and when they don't they kill power or cause driveability problems.
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I gotta send the bitch in. but when some shit puts me on the side of the road, or luckily in this case, at the top of the driveway it fucking sucks. especially when the damn thing costs more than $600.
The analog boxes do absolutely nothing when they work correctly, and when they don't they kill power or cause driveability problems.
EMI?
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It's not EMI, it slews timing signal badly or completely misfires.
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ok, Have you seen any reliabality issues with the Digital 6?
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i had a digital 6 a few years back, seemed to work great for the 2 step.
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I liked my DIS-4, till it died. Now, I'm knida uncomfortable going digital with MSD. Have had the 6A since '04 and it's never let me down, as with other MSD analog boxes I've had in the past. But the way JD is talking, I may be needing to retire the 6A when I boost the MR2. Runs well on motor, Just startingto question the added load and possibility of improper timing from the analog box.