staying n/t....what compression pistons to get??

[eclipse0508]

I am looking to rebuild my 420a. I am staying turbo, and Im confused on what compression pistons to get? I have been looking at the JE pistons and also Wiseco. Any info at all on this would be helpful. Also, if possible, can i get some links to buy these pistons, obviously the cheaper the better, but Im not settling for any junk parts.

Thanks guys.....

Also, what else should I replace besided pistons, rings, all major gasket, rods???

 

[VelocitàPaola]

In my opinion, 10.5:1 (or lower) is the way to go. I know there are 12:1 pistons available, but I've just heard too many stories about engines knocking at that compression ratio. If you're looking to beef up your internals while adding a little pep, 10.5:1 is you're best bet.

Both JE and Wiseco are fine piston manufacturers; whichever you pick is your own preference. Howell Automotive (http://www.howellautomotive.com/), Exile Racing (http://catalog.exileracing.com/), and Concept Illusions (http://www.conceptillusions.com/) will all carry what you need.

Besides pistons, rings, rods, and gaskets, you'll want new bearings, oil and water pumps (might as well), new timing components, and all new TTY or ARP hardware (main and head studs). While you're at it, a lighter crank pulley (think AF/X or Unorthodox) would be nice.

 

[eclipse0508]

what about staying with the 8.8.1 ratio?? what should I expect with the 10.5.1 ratio versus the stock? Also, should i stay standard bore or go over.020 or .040??

 

[VelocitàPaola]

What do you mean by "staying with" the 8.8:1 ratio? Your engine has a 9.6:1 ratio stock... 8.8:1 ratio is really only used for cars running a turbo or supercharger.

As a rule of thumb, higher compression ratios give more power, and lower compression ratios give less. Turbos and the like complicate things, but the rule still basically applies. With a 10.5:1 compression ratio, you'll gain a few horsepower, but you'll also probably need to start using 93 octane gas.

The bore depends on the shape of whatever block you're building. If there's no damage to the cylinder walls, I would bore everything out to 0.020" over to give the pistons a fresh surface to seat next to. If there is damage, then your machinist will have to tell you which pistons to order.

 

[bullettdsm]

Damn that Paul . Yeah ^^^^ what he said. Couple of good informative posts. I would reccomend using the JE 10.5's.

MB

 

[talnteddriver29]

The bore depends on the shape of whatever block you're building. If there's no damage to the cylinder walls, I would bore everything out to 0.020" over to give the pistons a fresh surface to seat next to. If there is damage, then your machinist will have to tell you which pistons to order.

Also, Re-ringing your pistons & Honing is something to keep in mind
VelocitàPaola,
What kind of Cross Angle Hatch pattern did you use when performing your Honing?(If you have) & what kind of # Grit stones did you use? Jus curious, cause i hear so many diff. stories, i cant get my facts straight. Lets say, if you were installing 10.5:1 Pistons in a 420A. I hear 30 degree angle is too low. So what is correct?

 

[4UH8ERS]

Also, Re-ringing your pistons & Honing is something to keep in mind
VelocitàPaola,
What kind of Cross Angle Hatch pattern did you use when performing your Honing?(If you have) & what kind of # Grit stones did you use? Jus curious, cause i hear so many diff. stories, i cant get my facts straight. Lets say, if you were installing 10.5:1 Pistons in a 420A. I hear 30 degree angle is too low. So what is correct?

For your honing needs just take the block to a machine shop and leave it to the experts its relatively cheap anyway. Now when you get new pistons for you bored application you have to get new rings. with je instructions are included.

 

[talnteddriver29]

Yea, im not gonna get my walls honed for my block. I was jus curious what kind of angle is good? and what #Grit stones are neccessary. Im no expert, but it wouldn't hurt to learn something new, which is why im on this forum Does anybody Know?

THX

 

[dr1665]

I am staying turbo, and Im confused

Your thread is titled, "Staying NT," so now we're both confused. If you're going to turbocharge the engine, 8.8:1 CR JEs will be the most affordable investment you'll want to consider. I have a set of four Wiseco ashtrays in my garage with less than 15,000 NA miles on them, so I'm set on ashtrays for a while. Stick with JE or Venolia imo. Now, if you're going to leave the car normally aspirated, I'd suggest jumping up to the 10.5:1 CR. I run a completely untuned, stock fuel system with a lot of portwork, aggressive cams, and 10.5:1 Venolias and the car will only knock around 5-15% throttle with the AC on when ambient temps are above 100* on 90 octane gas here in AZ.

IMO, these cars should have come with 10.5:1+ from the factory. It's a great place to be.

 

[VelocitàPaola]

VelocitàPaola,What kind of Cross Angle Hatch pattern did you use when performing your Honing?(If you have) & what kind of # Grit stones did you use?

I'unno. Honestly, I just took my block to the machine shop and let them take care of it. The block needed to be bored anyway, so they just honed it while they were at it.


And Brian, I think he meant to say "stay non-turbo," but I could be wrong. How about some clarification, eclipse0508?

 

[eclipse0508]

sorry guys, yeah i meant stay non turbo

 

[420Adriver]

let me know how those pistons work out because im considering staying n/t also

 

[4UH8ERS]

I'unno. Honestly, I just took my block to the machine shop and let them take care of it. The block needed to be bored anyway, so they just honed it while they were at it.


And Brian, I think he meant to say "stay non-turbo," but I could me wrong. How about some clarification, eclipse0508?

You in a hurry V? or drunk? I know you don't normally spell that way.

 

[dr1665]

sorry guys, yeah i meant stay non turbo

Roger that. If you're planning on staying non-turbo, I think this might be the best course of action for you. You'll get more bang for your buck.

If your bottom end is still holding it's own, and chances are it is, leave it alone. That's right, I said leave it alone. If you're getting up there on miles and want to freshen things up just to be on the safe side, pick up new, stock piston rings and bearings from Parts Dinosaur and have the cylinders re-honed so the new rings seat up nicely. Bolt up new water and oil pumps and an underdrive pulley if you've not already got one and call the bottom end done.

Why? Simple. If you're not boosting (or spraying more than a 75 shot of nitrous) your stock bottom end can handle just about anything you throw at it. If you intend to build beyond the factory redline (that is, wind the motor out beyond 7000rpm), then drop a couple extra bones to have your stock rotating assembly balanced. You're typically looking at around $400-$500 for forged pistons and rods, so keeping the stockers can save you $800-$1000 on your rebuild.

Put that money into the head. You heard me. The head. The only gains you get from installing aftermarket pistons are measured in durability - they are better able to handle the extreme temperature and pressure of turbocharging and heavy nitrous aplications. You will gain 4% more brake horsepower (think crank) by increasing your compression ratio by a full point. Stock is 9.6:1. Dropping in 10.5:1 pistons like I have will give you less than 4% more power at the crank. I'd be willing to bet that's all lost in translation before it gets to the wheels. Besides, you can mill the head to increase effective compression ratio. That's food for the search engine if you're interested.

Order yourself some PTCruiser lifters/lash adjusters and rocker arms, get some new valve guides, stainless valves, upgraded springs, new spring retainers, a set of level 2 or better cams, and some cam gears.

Now, find a used head in the classifieds or the sale/wanted section of 2GNT. Take the head and all the parts to your local, qualified machine shop. Have them give you a nice street port. Get too aggressive with the portwork and you'll lose bottom end power. Trust me on this. My car is a turd until around 4000rpm with a full on Fierro-Racing race port and oversized valves. Along with the street port, get a 5 angle valve job on those new valves, and have them install the new valve guides so you don't burn oil at idle. Let them install the valves, springs and retainers and then mill the gasket mating surface true. You might also consider having them mill the head down as mentioned before to increase compression. This may result in your having to get jiggy with your timing belt installation, so again, do your homework before doing this.

Once you get the head back and have a nice new MLS head gasket ready to go in (don't forget all new timing belt components - belt, tensioner, pullies), be sure you have a decent exhaust system on the car. Bargain hunting can score you a header-back for under $300 complete. You just have to know what your priorities are - name brand propaganda or 4-2-1 header and full-on 2.5" I.D. catback with true hi-flow cat (not eBay shit pipe). Give your new new head a breath of fresh air with a K&N filter on the end of an eBay or home made short ram and be ready for some fun.

Now, after all this is done, you will still be shy of that always hopeful 200whp, but based on my experience with my own car and two other, very similarly built cars (daniel992gnt and bullettdsm), I can tell you that you should be well within your rights to expect in the neighborhood of 140-150whp. Yes. You'll still have your ass handed to you by many other cars, but if you choose your battles wisely, you'll surprise more people than you thought you could. A big benefit to going this route is that you will maintain your current economy - likely around 30-35mpg+ on the highway. More important thant that, you'll also have a blast driving your car to boot. You will have a real screamer on your hands.

Want to make it hotter? Sure. Learn all you can about Megasquirt'n'Spark (MSnS) to be able to wind that motor out to 8000rpm+ to make better use of a cam like the Crower 3s or Crane 0022s (or beyond). Get that head race ported (remember what I said about what happens to your bottom end). Consider individual throttle bodies and a custom, long-tube header to make some more power. Sky's the limit, really. All the power is made in the head - it's just that we're finally getting to the point of actually using our heads!

Decide this isn't what you wanted? Fine. You can park the car, yank the head, throw your stocker back on (if you still have it), sell the cams and gears separately or with the rest of the head. Neat thing about a fully built race head - it weighs about 30lbs and fits under your bed or on a shelf in your closet. You can carry it into the UPS store and ship it all together if you want. Chances are, you might even be able to get some decent money out of it if you had to.

Damn. I guess I was feeling bad about not being very active over here lately. Hope this makes up for it. Someone have Chris send me a shirt or something, will ya? It would be ironic to see me sporting a DSMtuners shirt, but I would. Haha.

Okay. Now I'm talking out my ass. Time to go!

Latz

 

[VelocitàPaola]

Hey Brian, copy all that into a new thread called "All Motor Power Stages" or something, and I'll sticky it.

 

[bullettdsm]

Geez Brian, don't make me have to give you more greenie points ! Great informative post. (again).

Just a couple of "food for thought"s;

I chose the 10.9 comp (10.5 JE's with .020 shaved) for a couple of reasons. Yes the increase in power, but I also knew because of my cams, port and Jeep TB that I would want a little more "pop" in the low end. The high comp gives you just a little bit (yeah, not so noticeable on my set-up but it is there).

You also will want to get a bigger TB (especially if you are porting the head). You've got to be able to take advantage of the increased flow capabilities of your ported head (Brian is correct about the heads: they are the key to unlocking power - how is the question). The jury is still out on the best size TB. I had intended to do some dyno comparisons on the 55, 57 and 60mm TB's, I just could not find the time. Having run the 55 for a little bit and the the jeep 60, I would say the more "daily driver" of the two would be the 55. The 57 I made myself but I only put on to see if it worked. The 60 definitely seemed to have more power in the top end but lost in the bottom end.

Do not order a 4-2-1 header off of E-Bay. You will probably not get one. I ordered two of them only to have to send them back because, even though they advertised as 4-2-1, they were actually 4-1. The 4-2-1 in general will give you a little better low end (I actually ended up going with a 4-1).

Just a side note on MPG. Went to Vt this past weekend. 520 miles round trip. Came back to Ct to go racing did not even use a full tank! 60? miles city, all the rest cruise set on 72 highway. I got close to 40 mpg on the trip. I could not fill the tank to find out for sure because I had to go racing and I actually had use up some of the gas in the tank so I could get down to empty. Nothing like a Saf-c to help you out .

Just thought this might help you out with your decision.

MB

 

[dr1665]

Hey Brian, copy all that into a new thread called "All Motor Power Stages" or something, and I'll sticky it.

Haha. Sorry, Paul. Already did that once before.

link

Heads are cool. (circa 07.15.04 - just about two years ago this week!)

You must be logged in to view this image or video.

And Mark is currently the fastest, most powerful all motor 2GNT in the country right now, so be sure take his words to heart. He and I may have disagreed in the beginning, but he's proven himself to know what the eff he's talking about and definitely has my respect!

EDIT:
Just thought I would also mention that Mark's use of standard sized valves helps to keep air velocities up, likely helping him to make more useable power than I do. As I mentioned, my engine begins to come alive around 4000rpm, but the stock ECU I'm running until I get off my lazy ass and get this MSnS installed begins to pull timing and dumb things down around 6000rpm. Once the MSnS is installed, I intend to set a 9000rpm redline on the car and see where the power begins to drop off, at which point I'll initiate a soft touch rev limiter to begin pulling timing so I can *feel* where to shift gears to stay in the power band. Let's just hope the timing belt holds!

 

[VelocitàPaola]

Haha. Sorry, Paul. Already did that once before.

Oh... ok... I see how it is. Well, I know where your loyalty lies now...



(just kidding, I always knew where it lay )