Thread: Forged internal opinions

Hey guys, if anybody has been watching my thread you know that I had a few unexpected problems with the gtir that wasn't known when I traded for the car. After tearing down the block I found that it had 3 cracked pistons. So the block is getting checked, cleaned, machined, and crank polished. I need to at least buy new pistons and I'm thinking I'll probably go ahead and get forged pistons and rods.

My questions are for you all that have run different ones like CP, JE, Mahle, Eagle, Wiseco, Supertech, Etc...

Opinions, pros, cons, value, performance.

My other question is when buying rods, are they different for the gtir since from what I understand it uses 19mm rod bearings and if I remember correctly DE uses 17mm.

Thank you!

The stock GTi-R block will handle 450-500whp all day long. Maybe try and buy this long block and part out what you don't need? http://www.sr20-forum.com/forced-induction/51590-wa-pulsar-gtir-long-block.html
I know I didn't answer the question that you asked and I am sorry for going off topic but I just don't see the point of spending all that extra money for something that isn't necessary for your power goals. You will also have less down time and less man hours (time is money). If you were to sell the head you don't need, sell the tomei cams in the engine that I posted the link to, the intake manifold, the spare crank and end up with a spare clutch or if you sell that too you should end up paying next to nothing and could have the car running in a weekend. I also see more issues with built engines due to builder error than with stock engines. The stock engine will handle more whp than your setup can throw at it. Unless you are looking to run 500+whp all day long I just don't see the point in building an engine, especially a gti-r.

Yes, buying that block that you posted would be cheaper but it says local pickup only and I live no where near there and even if I did, I don't have a truck anymore to haul it.

Yes, I could make the money from parting out the gtir but the time to try to sell the parts or what is a reasonable price and hopeing that everything sells and your not sitting on parts for a year is just not feasible at the moment.

I know I'm not shooting for the top hp sr but that doesn't mean I should do it half ass and not be happy with it. Maybe I'll want to do more with it later.

People say the stock DET pistons are good to 400 or something but I have 3 cracked ones sitting on my workbench that say otherwise. I highly doubt the stock t28 would push that number.


I thank you for your help and info and I understand what your saying but in this thread I'm just looking for the info I asked in the first post.

I currently have Wiseco 9:1 forged pistons in my de-t. They've only been in for about 9 months, but they seem like good quality pistons. The only other pistons I've dealt with are JE, for a 355 build. Sold that car, and they are still running in the engine, even with the new owner randomly beating it.

As far as rods go, I also have BC Sprotsman rods in my engine. They are H-beam rods, and are rated for 200hp per cylinder. They are a little less expensive than the I-beam or 625 rods, but as long as they hold what they are rated for (which I am nowhere near), they are good enough for me.

I run 18 (effective) psi of boost on occasion, and run 7-10 psi daily. I gave everything a good break-in, so hopefully I won't have to worry about my rotating assembly in the future.

The stock t28 power is not what cracked the pistons, it was more than likely detonation from any number of different things that can cause detonation including over boosting from the stock t28. Just because you have a gti-r engine with 3 cracked pistons from a t28 means nothing about the power that the engine can hold in stock form. I will leave others to answer the question that you asked.... Most off the shelf aftermarket pistons & rods are pretty similar besides a few grams of weight and either I or h beam design unless you are looking for some rated over 7-800hp. CP & JE off the shelf pistons are about the same as far as I have seen in regards to what they will handle power wise. I would try and get 9:1 pistons if you are going to bother to buy forged pistons.

Thank you, this is the kind of info I'm looking for. I checked out that link you posted. It looks like they make a different rod for the 19mm bearings but it's quite a bit more expensive. The sportsman rods would be good for what I'm looking to do but I'm not sure that it would work with the gtir crank.

I am running cp 9:1 piston and manley h beam rods. Any decent machine shop can machine your rods to accept a 19mm bearing. I can tell you most aftermarket rods will be 150-200 grams lighter each than the stock gtir rod. the pistons will also be lighter as well. less weight equals more power.

My first build I used CP 8.5:1 86.5mm pistons with Eagle H-beam rods. That combo is good for about 700whp reliably. Some honda guys have pushed eagle rods to over 800whp for years without issues. I was at roughly 550whp on occasions without issue and over 430whp daily pump gas. Again on dissasembly everything was in beautiful shape. Pistons had no wear on them or the skirts, Rods were perfect as were the bearings. This is a typical and pretty cheap build setup. You can pick up that piston/rod combo for 740 shipped roughly.

If your pistons had cracked ring lands it probably left marks on the bore so your block is probably gonna have to be overbored to 86.5mm.

If you want higher than 700whp then CP's with a good I-beam rod such as Manley Turbo Tuff or Crowers would be more than plenty and can support over 1000whp. On the pistons you would want to get the upgraded tool steel wrist pins as the wrist pin becomes the weak point.

As far as other pistons, Weiscos are not as well designed as the CP's and have been known to fail at many hp levels from under 500 to over 700whp, usually its the bottom half of the pistons breaks away. They are quite thinner compared to the cp's.

CP's seem to be the piston of choice for the honda guys with big builds. They have been out there a long time and produce great stuff.

One of my friend who builds nascar style motors in a race shop swears up and down on Mahle pistons.

I've used Ross pistons on 2 builds so far and they are both still going strong. One on a 12.5:1 NA 3L and one on a T60 20psi boost daily 3L (both z car motors). Haven't built an SR (yet).

The NA car is starting to see road race use at least once a month now.

Good to know. I was thinking I should move up to 9:1 to help the car not feel doggy out of boost. The lighter pistons and rods would be nice. Do you happen to know if machining the rods will have any other effect on performance? Ive rebuilt a stock sr20de before but all the bearings were still standard and everything went smooth.



Thank you, you vids are always fun to watch and I was hoping you would chime in here. I have seen the piston and rod sets you are talking about. For under $800 it doesnt sound like a bad deal. I know 8.5:1 would be the safest but I have 94 octane at the pump here and its the only pump gas I use in my turbo cars so I think the 9:1 would be fine. We also have 114 and 116 at a pump a nearby for higher boost levels. I talked to my maachine shop and he said the bore mic'd out to 87.02mm. So im gonna have to go with 87's and file fit rings. Im with you on the CP pistons, it sounds like the way to go. I have also heard some differences on the Wiseco products and will probably stay away from them. My main thing I need to figure out is the rods now.



I heard great things about Mahle pistons in V8's but havent heard much of them with the 4 cylinder cars. I used Mahle rings in my LS6/LS2 im building. I forgot about Ross pistons. Ill look into them also.