Rafa

iTrader: (22)

Does anyone know where I can get a set of MSM 9.5:1 CR Pistons?

Also, where could I send them to be coated?

Thanks

patsmx5

iTrader: (16)

Why MSM pistons? And why triple coat them? I'm guessing you're building a motor? If so, will you be installing forged rods?

If you're building a motor and putting forged rods, go ahead and put a set of forged pistons too. No reason not to really.

Rafa

iTrader: (22)

You're dead on. My motor finally died Friday night. I've been reading these last days about pistons (both forged and OEM) and had decided not to mess with forged pistons. I read Samnavy's and Rotornut's threads. I'm not going to be going above 18 or 20psi at any time. In fact, I'm sure the engine would only see that kind of boost very sporadically.

I'm indeed going to use forged rods.

I guess I'll have to use forged pistons anyways because I've been searching all day for MazdaSpeed spare parts and have not found them.

patsmx5

iTrader: (16)

Well, it sucks that your motor died. What happened to it if you don't mind me asking?

The stock pistons are not bad. If you don't have detonation, and you keep turning up the boost, you will bend a rod before you break a piston from too much power. However, most engines are not broken from too much power but are in fact damaged from some form of detonation.

That said, as far as I know, MSM pistons are the same as 99-00 pistons. Just a 9.5:1 piston. Personally I would run a spec less compression for peace of mind. Running less static compression will give you a much larger safety cushion when tuning and driving. If it were a race car you would raise the compression as every HP matters and you have to build a motor that's on the edge to be competitive. But this is a street car, no?

For a daily driven car, I'd stick around 8.5-9.0:1 compression. This will make for easy tuning and ultimately a safer, more reliable setup.

Just an arbitrary example, but say your running 9.5:1 compression and 18 pounds of boost. There is a 1-2 degree range between the timing value that makes Max power/lowest EGT/highest average cylinder pressure and the timing value that produces knock. Where as an 8.5:1 compression motor and 18 PSI would have a 4-5 degree range between the timing value that makes max power/loweset EGT/highest average cylidner pressure and the timing value that produces knock. Granted in this example the 8.5:1 motor, all other things being equal, will make less power. But he could simply run 19 pounds instead of 18 and make the same power with a larger safety margin. Having a safety margin is critical for a daily driven car.

Ben

iTrader: (33)

These guys are great for various coatings and finishes. Evans Performance Products,atlanta,cryogenic processing,REM finishing,gear polishing,dry film lubricant coatings,marine race engines

sixshooter

iTrader: (12)

Wow. Sorry about your engine.

What happened?

+1 on lower compression. And +1 on forged to make sure you don't have to do this again.

Rafa

iTrader: (22)

I'm totally at fault for blowing up the engine.

Let me sum up what happened; I've been complaining ever since my tuner first installed my AEM about 2 problems:

1) My car would not compensate in idle for the A/C when it was on and it would die and;

2) as soon as I would turn the A/C for a little while my coolant temps would jump through the roof. Let me give you an example: I could run my car all day and even when driving it hard, the temps wouldn't go above 200*. If I turned the A/C on for 10 minutes I would see temps around 225-230* in less than 10 minutes. So I asked my tuner's head mechanic and he told me that he suspected that my base timing was too retarded.

I proceeded to check my EMS and found that indeed my tuner had set it up at 5*. I changed it to 10* (or so I thought ). Somehow, what I did was change it to 15* instead. I didn't discover this last fact until it was too late.

We checked the compression on the car Saturday morning and confirmed my suspicions: Piston #2 is dead (r.i.p. ).

patsmx5

iTrader: (16)

Hmm. Are you sure that the engine was actually idling at 5*? IE-put a timing light on it and verify it? I just wonder. I've run this timing map for a while. I idle at basically 20-21* all the time. Doesn't hurt a thing and as your tuner noted, it helps to keep it from overheating at idle.

Did it go out with a bang? Throw a rod or anything crazy? Did it die at idle/cruise/wide open? What kind of compression did you get on cylinder 2? You'd have to put base timing at idle to like 30 degrees and let it run like that for a few seconds to actually break a ring landing or something. Basicaly it would have to detonate, then knock. If it happens to run fine and only dropped a cylinder, it could be a stuck valve.

Anyway, this is the timing map I've run forever. Idle has been tuned like this for months. Doesn't hurt a thing. (also not I cropped the picture properly so Braineack won't have a fit.)

Rafa

iTrader: (22)

Thanks Ben. Do you know of anyone who's gone that route?


I just explained what happened when I replied to Pat's post so I'll take this opportunity to explain the reasoning behind my thoughts on higher (non forged) pistons:

Someone (I think it was Ben) posted a reply in Samnavy's old thread where he suggested y8s' results with 10:1 compression pistons and that got me to thinking that maybe it could work for me.

Pat asked me whether I planned to use my car at the track; the answer is: yes and no. Yes because I plan to drag it once in a while and also because I have the possibility of taking it to the track with a group of friends quite often and, no: because I won't be formally racing it against anyone so I can stop whenever I please.

Am I mistaken when I think that the higher compression pistons will allow me to see boost earlier in the rpm band? If that were the case, I'd be interested in the 9.5:1 pistons or 10:1 pistons. I'm using a T3/T4 turbo and I have to keep it. I can't afford to buy a new turbo right now. This new issue will mean a $2000 extra expenditure and the timing couldn't be worse. My youngest son is going to be entering a Masters program at SMU this coming August and we've been saving for that.

Sorry for the length of the explanation

patsmx5

iTrader: (16)

Higher compression does help some. The "general rule" is no more than 4% increase in power per full point of compression. (ie-from 9:1 to 10:1 would be up to a 4% increase in power if tuned properly) However, you can't just go up to 743:1 compression and increase power by 2836%.

Whether it helps "spool" is highly debatable. I've heard people say it does, I've seen dyno graphs that "prove' it does, and I've seen real world examples where higher comp. hurt spool. If I look at the physics aspect, I'm inclined to believe high compression does not help spool. Also my real world example I've seen says the same thing.

Rafa

iTrader: (22)

****, you have good questions! You make me feel reaffirmed in my mechanically challengeness!

I'm sure it was set at 5* because we checked it at my tuner's shop. What happened was that they took out the timing light when I mentioned the symptoms and I connected my laptop and was able to confirm it. Both would say 5* at the same time.

The problem as I see it Pat is that when I changed my base timing to 15*, I inadvertently advanced the timing map by 10* all over. We did this at 8 pm and I took my car out for a short spin and to fill it it up with gas. The fuel station is about 3 miles from my house. I drove there with my oldest son and filled the tank. On my way back, I began to notice a sound like that made by a loose chain when it rattles at around 4,500 to 5,000 rpms and my knock light was really flashing! I told my son that something was wrong but he insisted it had more to do with my exhaust hitting the butterfly brace we had just installed. So we got back to my apartment and he asked me to let him drive it. The poor soul called me 10 minutes later to tell me something was really wrong with the car and that it felt it was running on 3 cylinders. He asked me what to do and I told him to bring it back. The rest is history; the car was indeed running on 3 cylinders. I called the mechanic the next day and he came over with the compression tester and verified that piston 2 was dead.

patsmx5

iTrader: (16)

Ha, don't feel bad. We all have our strong and weak points.

I should have said this. Did you ever verify that the TDC mark on your harmonic balancer is indeed TDC? That's what I meant to ask. Because it could have slipped and you set it at say, 5* indicated, but it was actually 8, or 10, or 16, or... see what I mean? Easiest way to check is to pull a sparkplug and put something long and slender down the hole and let it rest on the piston and stick out the valve cover. A long extension, straightened coat hanger, etc. Then turn the motor with a wrench on the crankshaft and watch the coat hanger go up and down to find TDC. Once it's there, you look at the harmonic balancer and it should be dead on the TDC mark.

Granted, if you inadvertently advanced the entire timing map by 10*, then that's likely what killed it. But it still would be a good idea to verify the balancer was indeed correct.


Anyways, I hope you get it all straightened out. I remember you were having oil problems with that motor before anyways. At least now you can make it all new again! And stronger to boot!

Rafa

iTrader: (22)

This explanation is good enough. I'll go with Supertech's forged pistons. That's the cheapest I've found.

Rafa

iTrader: (22)

I'm at least satisfied that I did everything you mention here. I had my mechanic double check whether my timing belt was indeed correctly installed.

I know for sure I did increase my timing by 10* because the first thing I did was to hook it up to the laptop and open the AEM program; there in front of me, I could read 15*.

Many thanks for your assistance.

Has anyone in this forum used Supertech pistons?

patsmx5

iTrader: (16)

Hustler has a set in his motor, 8.6:1 comp. IIRC. Y8s also has a set of these, but hasn't installed them. Most run the Wiseco's. I'm sure either is fine though. I'd like to see some specs on the JE/Wiseco/supertech for comparison purposes. IE-see how much metal is behind the first and second ring landings, weight of each piston, things like that.

I need to do some research on pistons one day and figure out what I'm gonna use.

Rafa

iTrader: (22)

Here you go Pat: BELFAB RACING PRODUCTS

And here's a quote at the bottom of that page: "Features:
Forged from enhanced 4032 alloy and CNC machined
Contact reduction grooves are standard.
Honed & reamed pin bores for precise fit.
High tensile strength and evenly distributed hardness.
Pins and wire locks are provided with the pistons.
Withstand up to 42psi of turbo boost, w/alcohol, w/o any problems
A 2 or 3 forging steps process yields a fine structural grain oriented in fibers in the same direction of the stresses.
Wrist pins are constructed of cold extruded chrome moly steel for high strength to be used with wire clip locks"

I like the fact that these are 4032 alloy.

Ben

iTrader: (33)

Rafa, the argument for forged pistons is that they are tougher in the face of poor tuning. Stock pistons like to fall apart, especially at the ringlands, from detonation (ie poor tuning). Forged pistons are incredibly resilient and much less likely to fail under the same conditions. Unfortunately, since nothing comes free, they are potentially more damaging to cylinder bores at cold start. The phenomenon of "piston slap" occurs due to much greater thermal expansion and contraction of forged pistons compared to the stock hyper pistons. The greater distance between cold pistons and cold cylinder bores allows for contact, and potential eventual block damage.

Arguments for compression ratio can go either way. Personally I am a fan of higher compression. Higher compression should lead to better spool, better response, and better economy. The trade off is less margin for tuning error.

Something to consider is that headwork will reduce your compression ratio. I have a set of OS JE 9 or 9.5 pistons (don't remember) that I've been sitting on since I was planning a 400hp T3/T4 build of my old car... However the little bit I've driven my new 10AE has me convinced that I'd be a lot happier with starting the powerband early and only going for the 300hp range. Subsequently, I am considering headwork with high compression pistons, 10.5 or 11:1. After the headwork, actual compression should be around 10:1 or so. In the past, due to crappy engine management options, high compression pistons haven't been an option. However new options are more precise and don't have the spark scatter issues seen previously. I am confident in tuning ability and think this would get me to my goals in a safe manner.

Take a look into setups of Matts Yates and Kock to see what compression with big turbo can do for you.

Rafa

iTrader: (22)

Ben, thanks for that explanation.

As usual, I've got some dumb questions:

1) I specifically asked my mechanic about the honing job done locally since that's the part that really worries me. He told me there are good shops here doing it. He said, that this part, along with a good build up, would really reduce the chances of facing piston slap. I understand, from what I've been reading on the subject that the first 600 miles after the build are critical. I plan to follow FM's procedure for it.

2) I trust your judgment on mechanical aspects of Miatas so I have to ask: I already have a small headwork done on my engine (mild porting and **** like that) but I really don't want to deal with a 99 head. Local tuners are not too good and mine just doesn't have the time so I'm on my own in that matter. So; are you suggesting cams and valves?

3) I totally agree with you in regards to the best HP range for our cars; I think anything around 300whp for a dd Miata is just perfect (maybe a little too much in some instances) so that's my ultimate goal. The only issue I still need to resolve (without spending too much extra $) is whether I can get a T3/T4 to produce boost at the right powerband. I don't think I'll be able to see full boost by 3,200 rpm with it. I would love to get my hands on a T2871 but that would mean changing the manifold too and that is totally out of the equation (at least for the next 8 months).

4) I've seen some 11:1 compression forged pistons. My final question is: do you think I would be risking it too much if I buy them?

Thanks

patsmx5

iTrader: (16)

FWIW, I see full boost by 3200 with my GT3271. Very good spool considering how big the turbo is. Journal bearing, 52 trim comp, .78 A/R hotside, mild tune, MBC. I have a 99' motor with extensive head work, but all stock components. Headwork is huge when it comes to spool up. And also the folks Ben noted are running 01 heads, which flow as well as a 99' but have the advantage of VVT.

You can do a 300whp setup with 11.0:1 compression. But you'll have to tune it well. It won't have as much room for error as a lower comp motor. Make sure you have a good tuner if you decide to go high on the compression.

And as far as the bottom end goes, it's not how they hone it. They will bore the engine a certain size as to maintain a certain piston/cylinder clearance. Exactly what clearance they choose is based on the piston type (forged or cast) as well as what the motor will be used for (N/A, turbo, Nitrous). Make SURE you have a very good machinist do the engine that knows how to build race motors. It's critical.

RotorNutFD3S

iTrader: (33)

FWIW, I'm using tri-coated OEM pistons done by the shop Ben recommended. I couldn't justify the cost of forged when no one has had any issues with the OEMs unless due to poor tuning. Also because I daily drive my car and didn't want to risk piston slap wearing the engine any faster than necessary. My goal was a simple mild build to strengthen the weakest points: rods and rings.