That still doesn't make sense. You're saying LTH aren't necessary on a SC unless you want maximum power (that's exactly why I'm installing them), but they are necessary for NA- if you want maximum power out of it. In both cases, if you want maximum power, that's what LTH is for.

I think what you're trying to say is money is better spent elsewhere for power figures.

My preference is to avoid the additional weight/complication of a sprayer setup and have better exhaust flow 100% of the time. Everything I've done in this build (excepting the SC vs turbo) is to maximise airflow and efficiency. It's not a value for money max-power setup, for sure.

 

I mean, that would be one way of looking at it, but as long as cats are still in play there is no meaningful additional flow from LTH to something like Tomei. Tomei did MORE R&D than PPE BTW, the tubes are only going to flow so much, the benefits from the LTH as far as flow is concerned is from the lack of cats (when compared to another good header)

Like I said, I'm not about the catless life and it is really not about the money either. The kit is capable of 500hp on stock headers, my target is 450-500, I have no need for more.

 

That's cool man. I'm not trying to convince you to use LTH over Tomeis in your setup. That all makes sense for how you'd approach a build.

In general though, in terms of comparative performance, unless you've seen back to back testing of PPE headers vs Tomei, I'm not sure any of us are in a position to make claims one way or another. Do you actually know Tomei did more testing than PPE? Is that documented somewhere?

At the end of the day, the Tomeis (and any other shorties) are still designed with the size constraint of having to fit with cats. That's a compromise. Longer primaries in LTH allow for smoother transition at the collector so in theory there should be some performance to gain. My gut feel is there would be marginal difference between the Tomeis with cat delete and PPE LTH (PPE > ISR so not all LTH are created equal), but we wouldn't know for sure without a back to back. Unlikely we'll ever find out though.

It's possible down the track I'll have a Y-pipe built with cats to keep the cops happy, but I'll still have the scavenging benefits of long tubes.

 

Tomei has all the R&D on their site on all the different iterations. PPE never made that available to my knowledge, lack of transparency = little to no R&D IMO.
let's keep it real tho, the PPEs are probably better, but I'd probably take the Powercraft (catted) ones over PPE even without the cats as I like their design better.

LTH gains are all about the last sentence you said scavenging, make no mistake, if I was ok with running catless I would go with LTH.

There is also ONE thing that differentiates our builds overall. You are using much more aggressive cams than the ones I will be using, you have a more aggressive exhaust cam in relation to the intake, while mine will be using the HKS cams, they are only 264s with a 10.5 IN and 10.2 EX lift.

So overall, we picked the best for our given builds and desired power levels. The HKS cams peak out at 6800rpm on their SC kit, and I'm targeting a 7k redline, so it all just makes sense to me.

 

Just notices the gauge flip on the RHD

 

Hey Tim,

Does your Z have rev hang with the HKS kit? When I let off the throttle I gain like 300 rpm, as if the BOV isn't opening fast enough. I just installed a Turbosmart Kompact and dialed it in 2 turns from soft and it's basically the same as the HKS BOV. I will adjust more this weekend, but I wanted to see if you ever had that issue as well? Thanks!

 

Hey Green, I've experienced what you're talking about but I'm not convinced it's the BOV (although it's still plausible), at least in my case. I've played around with the tune I think it was more to do with idle ignition timing. So clutch in with no throttle would rise momentarily because the engine was producing too much torque to drop.

I managed to dial mine out but I've got kind of the opposite problem right now with mine. I'm a little over trying to fix my idle return so I'm going to leave it to the tuner once engine break in is done.

 

Good to know! Thanks for the info. I dropped a built DE into my Z and I’ve got the tune at 18 degrees of timing and the SC is about 12.5 PSI. Still need to get it on the dyno but I’ve got an oil leak somewhere I have to chase down first.

oh also, does your BOV still chatter or did you get that dialed in?

 

According to a few tuners I've spoken to, 18 degrees is pretty high for Zs at or around idle. 15-16 would be more typical. Give that a shot and see if it makes a difference.

 

18 on the top end. No knock currently. 8.8 compression 91 octane.

 

Update:

Made 420whp 355wtq

8.8:1 compression built bottom end
JWT S2 Cams
91 Octane
HKS GT V2 100mm pulley (11.6psi) I've gotten up to 12.5psi on the street so I am not sure why it was a bit lower on the dyno. Possibly just getting hot or slipping a little.

On my old motor it was a RevUp 140k miles bone stock with the 110mm pulley made 313whp on a Mustang Dyno so it was prob about 340whp on a Dyno Jet.

I bought the new built motor for a steal so I didn't get to choose the compression. But since I drive this car all the time, I do like the added benefit of zero knock whatsoever.

 

Car looks rad. I imagine the piston’s compression ratio is holding it back, but I wouldn’t be sure how much though.

 

Thanks, dude! I painted it in my garage over Christmas break, it was definitely a learning experience!

The CR is definitely holding it back. Ideally that motor is built for a big turbo with fat boost and E85.

But since it's such low compression I am able to run really high timing with only around 12psi and the motor is super happy. I may later this year go to a mid mount kit and run e85 and get a lot closer to 550whp.