Built engine question - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

86 driver · 09-02-2015, 01:53 AM

Are forged pistons necessary or can I just use rods? I want to keep the same ratio as stock anyways.

There hasn't been any reported cases of busted pistons to my knowledge. Only busted stock rods.

FYI my goal is to be around around 450 hp when it is built. Valve springs will be installed as well. What are your opinions on stock vs forged pistons?

EAGLE5 · 09-02-2015, 02:24 AM

Replacing one without replacing the other seems a bit of a waste.

megamarines · 09-02-2015, 05:25 AM

Better to just make sure everything is on the same page. Despite the main weakness being fixed, it opens up other problems for parts not up to that level.

350matt · 09-02-2015, 07:01 AM

I think the stock item is pretty good but if you're aiming for 450Bhp then I think you'll have an easier time getting there with a slightly lower ratio and more boost I mean 10.5:1 is still a reasonable level of ratio for a boosted engine

celek · 09-02-2015, 09:36 AM

With the stock compression you are fighting Knock to make power. Requiring Higher Octane to compensate. Spend a bit more for Pistons at the same time. I can tell you rods and pistons in our block with Valves springs can yield OVER 700 HP.

smudge · 09-02-2015, 11:04 AM

I still envy you Yanks with your e85 fuel

wish we had that in the UK

weederr33 · 09-02-2015, 11:56 AM

Quote:

Originally Posted by smudge

I still envy you Yanks with your e85 fuel

wish we had that in the UK

'Murca!

smudge · 09-02-2015, 12:25 PM

Quote:

Originally Posted by weederr33

'Murca!

Can I have some of that sweet, sweet freedom sent over via bald eagle please?

86 driver · 09-03-2015, 12:54 AM

Quote:

Originally Posted by celek

With the stock compression you are fighting Knock to make power. Requiring Higher Octane to compensate. Spend a bit more for Pistons at the same time. I can tell you rods and pistons in our block with Valves springs can yield OVER 700 HP.

That makes sense. I'm running a flex fuel kit, so it will be on e85 for that kind of power. My tuner was saying that lowered compression wasn't necessary.

I will definitely look into forged pistons now. Thanks for the heads up.

celek · 09-03-2015, 10:03 AM

Quote:

Originally Posted by 86 driver

That makes sense. I'm running a flex fuel kit, so it will be on e85 for that kind of power. My tuner was saying that lowered compression wasn't necessary.

I will definitely look into forged pistons now. Thanks for the heads up.

Does your builder realize its a factory 12.5:1 compression motor?

EAGLE5 · 09-03-2015, 11:11 AM

Lots of big power cars on stock compression levels. A good tuner can handle it.

86 driver · 09-10-2015, 07:43 PM

Quote:

Originally Posted by celek

Does your builder realize its a factory 12.5:1 compression motor?

Yes. I thought the same thing, but he said that's the way he prefers it.

aagun · 09-10-2015, 11:47 PM

Quote:

Originally Posted by smudge

I still envy you Yanks with your e85 fuel

wish we had that in the UK

UAE TOO PLZ

stevo585 · 09-11-2015, 12:16 AM

Quote:

Originally Posted by 86 driver

Yes. I thought the same thing, but he said that's the way he prefers it.

Helps keep the lag down. And if your running e85 full time even more reason to keep stock comp. ratio.

09-02-2015, 01:53 AM	#1
86 driver Member Join Date: May 2015 Drives: 2013 FRS Location: United States Posts: 19 Thanks: 0 Thanked 1 Time in 1 Post Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Built engine question Are forged pistons necessary or can I just use rods? I want to keep the same ratio as stock anyways. There hasn't been any reported cases of busted pistons to my knowledge. Only busted stock rods. FYI my goal is to be around around 450 hp when it is built. Valve springs will be installed as well. What are your opinions on stock vs forged pistons?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Boost pressure for built engine	ChrisD	Forced Induction	75	01-06-2016 02:24 PM
Built Engine. Sprintex 335. GTX30r. other bolt ons for sale.	alexisfire02	Engine, Exhaust, Bolt-Ons	9	02-03-2015 01:42 PM
WV: 04 STI Low miles Built 400+ AWHP 33K on chassis 1500 on engine $25K	dakjones	Cars for Sale/Trade	6	09-03-2014 09:05 PM
Anyone has Stroked and Built FA Engine yet ?	Whitigir	Engine, Exhaust, Transmission	11	03-14-2014 06:31 PM
What is the best turbo for a fully built engine scion frs	SUB-ZERO	Forced Induction	41	09-18-2013 07:41 PM

09-02-2015, 05:25 AM	#3
megamarines Senior Member Join Date: Aug 2014 Drives: 2015 FR-S RS 1.0 Location: Walnut Creek, CA Posts: 368 Thanks: 144 Thanked 177 Times in 91 Posts Mentioned: 29 Post(s) Tagged: 2 Thread(s)	Better to just make sure everything is on the same page. Despite the main weakness being fixed, it opens up other problems for parts not up to that level.

09-02-2015, 07:01 AM	#4
350matt Senior Member Join Date: Jul 2013 Drives: toyota mr2/ Toyota GT86 Location: UK Posts: 438 Thanks: 3 Thanked 140 Times in 92 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I think the stock item is pretty good but if you're aiming for 450Bhp then I think you'll have an easier time getting there with a slightly lower ratio and more boost I mean 10.5:1 is still a reasonable level of ratio for a boosted engine

09-02-2015, 11:04 AM	#6
smudge Senior Member Join Date: Feb 2015 Drives: Supercharged GT86 Location: UK Posts: 287 Thanks: 75 Thanked 163 Times in 85 Posts Mentioned: 4 Post(s) Tagged: 2 Thread(s)	I still envy you Yanks with your e85 fuel wish we had that in the UK

User Name		Remember Me?
Password