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Thoughts on this built engine for my Turbo FRS
https://www.rallysportdirect.com/par...ru-short-block
Looking to build my engine. The shop I would take it to is recommending this engine. Any thoughts? |
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What turbo are you going to be running and at how much boost? |
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You can make 400whp on E85 without dropping the compression ratio.
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That’s jus what they recommend... Why would or wouldn’t you use a different compression ratio? The IAG described it as being safer for boost... I don’t care what hp number I make. I just want my engine to not blow up.
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IAG is a great company. Do it!!
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350whp on 91 and 425whp on E85 should be perfectly fine and safe on stock compression with forged rods/pistons. It’s largely on the tune and boost controller for safety once you have forged internals. The trade off is lower compression requires more boost to make the same power So you’ll have more turbo lag/spool up and less low end torque/throttle response, worse MPG, and less off boost power. but assuming your turbo can pump enough air you’ll have more top end potential. But with sub 425whp goals your probably better off with stock compression. Or do 12:1 or 11.5:1 for a happy medium. |
Pump gas is really the deciding factor, besides power potential and reliability. I would rather be able to make big power on pump gas than be concerned about low end power.
Are there many people making more than 300whp on 91? 350whp on 91 seems sketchy, even on a built motor. A built motor can help avoid failure from higher power, but not from preignition/detonation. |
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But not really anyone with a built block that kept stock compression and runs 91 that’s posted a dyno that I’ve found. Usually either lowered compression, or uses E85. Personally if I had E85 and only wanted sub 450whp i would keep stock compression, or only slightly drop it. And just keep the boost low if I ever had to resort to pump. |
Well that took a turn |
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I would run 10.5:1 |
Also, this post of this thread had this link, which showed the dyno below for a slightly modded WRX throwing down decent numbers on 93 octane.
http://i.imgur.com/MU08aj3.jpg That post led to this response, which I'll quote anyways: Quote:
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Sell the parts separately. I'm interested in the turbo kit and clutch and etc.... hahahha
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I really don't feel like that was necessary. You might not be a fan of his style, nor would a majority of people, but the 86 is known for having young and flashy owners with tastes on the more extreme spectrum, so I'm sure he could sell the car for at least $12k. No need to beat on the man when he is down having blown his motor and needing to sell his car for a loss. |
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Outside of the wrap, the car looks like any other car here, so what is your point? The $4k vinyl wrap can be removed in minutes. That car is loaded with high end parts. A new, built shortblock and a rebuild for $5k, and the car is capable of being a beast. Maybe the cost for the new owner can be offset by selling a few parts like the other two sets of rims or whatever. |
I really just wanted to know If this particular engine the IAG Stg2 with the lower 10.0:1 compression is a reliable option and worth spending the $9,000 it well take to have it installed. James my tuner says the lower ratio is not a good idea... The internet is filled with waaay to much misinformation and I seriously regret ever looking on it for any advice on this build... I guess I just drop the money on this and hope it runs. Shop says they cant tune useing EcuTek so i dunno what im going to tune it with. Sell my ecutek and buy a OFt i guess. Or hope that the same tune from HRi before will work on the new engine
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Look at every manufacturer on the market who has a forced induction motor. They all run lower compression. 10:1 is still high by many standards. If a tuner is balking at such a notion then perhaps it is because they don’t have experience tuning lower compression on this platform. Can they actually provide a reason why lower compression isn’t necessary? 400whp is achievable, but you will be making less than 300whp on 91. Why not have more while your building the motor and not being reliant on E85. It seems easier to tune the car for 91 and E85 with lower compression than trying to program progressive boost or boost by gear or something anyways. |
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You shop can’t tune using EcuTek? Is this the shop that tuned it prior to it blowing up? If that is the case I would look into a new shop/tuner. You have put a lot of money in the car. Buy used engine out of a junk yard. Look for a car that has not been modified not the lowest mileage. Take apart and put new rods/pistons/rings. Reassemble with the best of the parts you have. |
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It's weird that the shop have not tuned with ECUTek when it's the most used program when it comes to our platform besides OFT. Makes me doubt that shop a bit but can't judge. You can possibly have them install, then get James to e-tune it for you. Full Blown is a reputable company that made turbo kits and parts for our cars so Idk why people would say to stay away from them, when James do recommend it. Edit:Here's the link for IAG St2 Standard CR (12.5:1) https://www.iagperformance.com/IAG-S...g-eng-1210.htm |
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As for the tune you have from James, it is the same base tune. It will work so long as it has the same parts on the engine as before. CR won't affect the base tune. Lastly, consider my entire offer I sent to you via pm. I'm more than willing to help you out. I'm only 4 hours away. If you want to, pm me back and I'll give you my number and we can talk. |
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@Irace86.2.0. (for some reason can't quote) The thing is, we aren't seeing the whole picture of what @Conman wants from his car or what he had told to his tuner. So far, we only know two things of what he wants and those are it being a safe build and making 400 whp. His tuner might have said it might be a bad idea because if he wants the minimum or no turbo lag at all then having the standard CR helps alleviate that as much as possible. Until @Conman tells us what he wants from the car, any type of theory/build is usable.
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If E85 was plentiful, pump gas was rarely going to happen, 400whp was the limit forever, the car never saw a track day and long commutes required fuel economy then I would totally say leave the stock compression, but in any other scenario I would say drop compression.
This quote from post 14 says it all: Quote:
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Right on! Thanks; Yeah E85 is plentiful around me. I dont really see making any changes for more power after this. I might want to do a track day maybe a couple times a year, and weekend autoXs. Its going to be my daily for the spring, summer, fall but my commute is very easy. Only 12 miles, mostly highway... Only thing is i really wanted to be able to drive it cross country out to CA to visit my buddy and do a track day out there with him. But I might just need to buy a trailer and haul it if I want to do that... |
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I would just read that link I posted. Here it is again, but read more about what others said than myself; those who lowered compression: http://www.ft86club.com/forums/showt...pression+ratio In the beginning I was in the camp that E85 was enough for 400whp, that it only made sense to drop compression when wanting more power than that, or if someone was going to spend a lot of time on 91 octane, but it seems like if anyone is going to be doing track days, wants more power off E85, more power potential down the road, etc then might as well drop the compression. In fact, several guys with lower compression motors chimed in and their responses confirmed the benefits. You are in the E85 capital of the country, practically, so access isn't an issue, but for reliability, I would consider dropping compression, especially if you will be doing track days. |
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Just sharing some knowledge about what those companies prefer, not trying to tell you you're wrong. Many different ways to make power. |
Or simply there are more ways to skin a cat, netting same result/output at end.
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When these cars first came out, it was commonly thought that even 10:1 compression was high compression, and people thought with 12.5:1 that no way this can handle any boost, then people tried it and thought, OK it can handle it but 7psi is the limit, and then they kept testing it and pushing it and its been shown that even 12-13psi is pretty reliable on a stock engine. Many tuners in recent years now have changed their thoughts on needing to lower the CR stating its not really necessary, and often times not recommended.
New tuning methods, the cars ability to monitor so many parameters and give instant feedback, being able to adjust and tune so many parameters, and having both PI and DI, has allowed tuners to safely push these cars closer to the edge, as well as push the edge further out, allowing for safe reliable power with out needing to drop the CR. 400whp on E85 is easy to get with stock CR, I would possibly consider 12:1 for a slight added margin of safety and being able to push the car more in the future if desired. but much lower doesn't seem necessary or worth it on these cars, unless your shooting for some crazy numbers. Hearing from people who dropped CR stating its worth it or recommended doesn't really say much. I would much prefer hearing from people with built engines and kept stock CR and what their tuner said was the limiting factor for reliable power. |
I remember 35 years ago doing 10 to 1 on a 351 Windsor in my 73 Bronco. At the time that was a premium gas only engine.
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Another view on this are the stock motors built by Honda (I know different engine). I have seen even the type-r engines (both B and K series) push around 350-400 whp on stock blocks w/ boost (these are already running 11:1 or 11.5:1 CR iirc from factory) and still driving fine. |
It would be interesting to see 400whp at 10:1 and at 12.5:1 on the track. Specifically, would the temps be much different and would the cars still be putting down 400whp or would the 12.5:1 be compensating with ignition timing.
We have a few people who have blown built motors too. Curious what their compression ratio was. |
Maybe @Sportsguy83 can chime in. Didn’t he make like 553whp on a stock block or something freaky? Maybe 400whp is nothing, even for the track.
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552 on stock block, but that’s just a ticking time bomb..... I pushed it on 500 whp map, the 552 map was very rarely used. If I would have built the FA20, it would have been because I trust the shop that built it and wouldn’t ace any worries tracking it at 400 whp... but I don’t know if there’s any track record out there for built cars being used hard on the track at that power level. There has to be, but I personally don’t know. |
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