Effective NA Power Mods
 

I've read through hundreds of posts and reviewed dozens of videos on using FI to boost the GT86 power output. Initially, I was planning to go the FI route but am having second thoughts. I have experience with blowers on Mustangs so I have an idea of the issues that come with FI. When the 2017 BRZ was announced with the Performance Package, I really started to rethink the FI route.

I've been doing research primarily on this site on effective NA mods. While it is not clear that what has been developed for the 2013 - 2016 cars will translate directly to the new 2017 BRZ, I would guess that most of the mods will also be effective on the new car.

I'm asking for feedback and input on what I have planned for mods and if there are any other worthwhile/effective mods that I have not considered.

Exhaust

The stock exhaust is rather subdued and there is some power to be gained. I'm leaning toward a UEL catless header. I prefer the more classic sound of the EL headers but, from what I have read, it appears that a good UEL catless header does a better job of filling in the 3500 - 4500 torque dip. I don't know if I will change out the over pipe (OP) or the downpipe (DP) as there does not seem to be much power to be gained from either the OP or DP replacement. However, I have yet to find a good comparison of stock DP vs replacement catted DP so I'm open to input on DP replacement.

I do know that I will want to maintain a secondary CAT for a couple reasons. Unburned fuel is pretty obnoxious and, from my Mustang experience, a CAT is pretty effective at ensuring the exhaust sound is livable.

Intake

From what I have read, you can achieve almost all the gains available on the intake side by using a simple drop in filter (e.g. K&N). While not as pretty as a GrimmSpeed intake, a K&N is a lot less expensive and give 80 - 90% of the available gains. There are no significant gains for replacing the TB or the intake tube. I have used phenolic spacers in the past to help insulate the TB and I have also bypassed the TB coolant flow (actually heats the TB for winter conditions). Living in the south, I'll probably try these options but I'm doubtful that it will provide much if any gains in power.

Lastly, I've not read anything definitive on port matching the TB or the intake. With the new aluminum intake on the 2017, this is probably something I'll at least look at.

Tuning

I understand that a good tune for 93 octane and UEL header should provide a significant bump in power output and it can also prevent the CEL due to loss of the primary CAT. I live in NASCAR central so finding a dyno is not a problem. You can't swing a dead CAT here without hitting a tuning shop with a dyno (Pun intended).

I don't want to run E85 or other Flex Fuels. While available locally, its not available everywhere and I don't want the added hassle of swapping out tunes to accommodate the availability/unavailability of Flex Fuels in other locations. I'm also not sure of the long term effects of running high ethanol concentrations in the GT86. I've had some experience with ethanol destroying plastics and synthetic rubber materials not designed for long term exposure to ethanol.

Summary

I'm hoping to get in the neighborhood of 225 - 230 crank HP (180 - 185 whp) out of the mods outlined above. Is that a reasonable expectation? Am I leaving much HP on the table?

Thanks in advance for any input you can provide.

http://www.ft86club.com/forums/showthread.php?t=81493



Attachment 145728

I think you got it covered ........ with the exception of some stickers ....:thumbsup:


humfrz

Thanks Captain, but as I mentioned in the original post, I've been through literally hundreds of posts on this forum including the one you highlighted.

Thanks for pointing that out. I'd forgotten that the right set of stickers will add ~10 whp on a properly tuned GT86.

.
Attachment 145729

So, is that a no?

The Ace and PTuning Equal length headers seem to put up great numbers. I would have gone that route but the uel options were much less expensive.

I have KN filter, OFT, Axle back, and uel headers coming tomorrow. Thats my budget way of getting the most out of bolt on mods NA. Any more spent seemed like extra money for not much performance gain. The axle back was just for a bit more sound and non wimpy tips... My goal was to fill the torque dip area and put around 180+ to the wheels on a budget.

I think you will hit your goal based on what you have planned.

Ya I think there is some left on the table if you go your planned route. Fork out the extra $ to get the el sound you want and a great torque curve. I really want the ace header but it cost 3x the uel header I've got coming. To get the most out of it I would have to find a good tuner and get it dyno tuned which is more $.

Thats why I'm going with uel and oft will pretty much get you say 80-90% of your bolt on NA performance. That's my thoughts...

My post was in response to you having read many of the related posts, including @steve99's gospel, and expecting that there is something magical you haven't seen.

For NA mods I would do things which would concentrate on lightening mass and lowering MOI of parts while keeping it reliable enough for a DD....don't care about raising power levels as much as getting better engine responsiveness from an NA build. If you can up the redline you can up the power... costs $$$$ though.

Valvetrain and drivetrain would be the focus...exhaust and intake work are a given on any modded car.

Camshafts, rockers/lifters, valves/springs, lightweight flywheel, and reagearing the rear end is where I'd first spend my money/efforts for building NA with the FA20.

I was reading along thinking that the world has come to it's senses because nobody has suggested LWCP or LWFW, and there you go ruining it.

It is NOT POSSIBLE to get "more hp" by reducing the rotating mass of the engine or drivetrain.
It does not Make more HP or "free up" more HP.
Removing weight from the rotating mass will give you the exact same benefits as removing that same weight from anywhere else on the car.
Except by focusing your efforts on reducing rotating mass you will certainly see a huge decrease in the weight of your wallet.

The only noticeable change in "responsiveness" is throttle response when the car is out of gear.

It's not the loss of mass that is most important in a lightweight flywheel, it's the redistribution to give a lower MOI that is most important...

I don't know about you, but when I've installed racing flywheels with as much mass removed from the periphery as possible to drop the MOI, acceleration/decceleration of the vehicle noticeably and measureably increases - and has nothing to do with a 'power increase'. If you want an assembly to spin up quicker you can either apply more power to it or you could reduce it's MOI - thereby reducing the effort/time needed to accelerate/deccelerate it. Wheel selection is the same way, select the wrong wheels with unneccesary mass concentrated at the periphery and you just slowed down your vehicles acceleration/decceleration. Select a same mass set of wheel with a maximized low MOI and you just increased the vehicles acceleration/decceleration. Same mass, different result - all depends on how its distributed.

Like I said in my initial post, don't really care about raising the power level as much as letting the engine do it's job easier and quicker through MOI reduction. The goal of a NA motor build to me is to increase responsiveness (the ability to accelerate/deccelerate the drivetrain quicker). Increasing power level doesn't necessarily give you a more responsive motor - it can, but it's not a given.

ACE CS400 will destroy all UEL and most EL headers on the market, full exhaust and intake don't net the most power but the engine is a lot more responsive.

Pretty much any header, exhaust and panel filter with a proper tune should net you 180 whp.

With the tune, try to go with something like Ecutek and get your car dyno tuned rather than just flashing it with something off the shelf. You'll net more gains. I've seen a peak increase of 7 whp and 6 ft-lbs of torque between a custom tune and an ots flash.