HiCompression VS Turbo

[acidbug]

Very true..My bottle is empty right now..

LOL

 

[Installshield 2]

shield you are the man, i just need to find someone that knows what the internal spec is on the stock piping and hks rear section....worst case i just have them weld on the muffler to a header-back exhaust right?

I am almost positive that the stock piping for a P5 is about 2", only difference being the pipes were created in Japan and it is most likely in metric, so it could be like 2.045" or something goofy in order to fall on an even mm or cm measurement...

If it ends up that your HKS is very close to the stock diameter (in the 2" or very close region) I would try to sell it...Post it on E-bay or even the wanted/for sale section of this forum...Since it is obvious that the tip and actual canister are much bigger than stock on the HKS, the only thing in question is the pipe from the axle-flange to the leading end of the canster (the pipe before the muffler)...Like you mentioned, if you wanted to you could have that hacked off and replaced with a bigger pipe, but then it will most likely turn into a buzzy vibrating muffler, and will not last nearly as long unless the welder is very talented (welding stainless sucks)...so again I would try to sell it if it is smaller...and try to find a good price on the Racing Beat cat-back, or if you like the look and sound of the HKS, try the 5zigen Fireball cat-back (you can get that at www.planetperformance.com for about $500, the RB is more around $400 normally)...The 5Zigen is a little over 2.5" and the RB is about 2.375" in diameter...Both are just about perfect for you current and future mods listed...Too big will kill exhuast pulse rate, gutting torque, and too small will fizzle high end power( the stock exhuast was too small, so remember what it felt like in higher rpms? the cams, DOWN-PIPE and exhuast diameter were the main causes of that...you have already cured the leading cause)

But dude remember that all of this is probably only going to yeild another 5whp or so...if the HKS fits your needs, the price probably won't live up to the power gains for additional exhuast work...worry about the cams for now, and then the flywheel...I would just go with these exhuast options before the pullies, since pullies will make little difference in every gear but first (which the flywheel more than covers)...and with the cams and flywheel your engine will be begging to be revved, in which case these larger diameter exhuast options will be most beneficial...

 

[p5sundevil]

yah right now I am window shopping for an intake upgrade, i mean I love the sound of my ebay intake and I am already looking at an HKS or S&B filter replacement with maybe some CAI ducting but if I can find an nijen for 150 or under, even used, I think i would get it....still not sure though, not important right now.

After that I have decisions to make.
I have a brand new axle back ractive exhaust sitting in my room, i think it is 2.25 piping with a 3in tip on the straight through muffler. I would rather get something like 2.375-2.5in cat back custom exhaust and have them weld on a muffler. If the sale price of the ractive could cover most of the custom exhaust work I deem it worth it.

Otherwise Ill install the ractive and go on to my list:
header
cams
port and polished heads
flywheel/clutch upgrade (want to do both since install is in same location)
hi-flo2nd cat
and maybe pulley(s)(just cause I liek my off the line low end torque.

Then I will look at a turbo upgrade, like I said financially I see getting the stage1 spool with custom FMIC and ECU upgrade being the best bet. maybe even use a custom turbo(although with the little to no knowledge of techinical turbo specs I fear doing that)

 

[deckedoutmp5]

Then I will look at a turbo upgrade, like I said financially I see getting the stage1 spool with custom FMIC and ECU upgrade being the best bet. maybe even use a custom turbo(although with the little to no knowledge of techinical turbo specs I fear doing that)

If you are goin to go turbo just remember that when you mess with cams and other NA stuff, it will make a diff on the turbo as to timing and running right. we turbo guys dont even mess with cams they do nothing for us you can gain the power in boost. so what i mean is, if you keep all your aftermarket NA stuff on there you prolly wont be able to use a premade map, and you will have ot have lots of tuning done. just fyi future headaches warning from trav.

 

[Installshield 2]

If you are goin to go turbo just remember that when you mess with cams and other NA stuff, it will make a diff on the turbo as to timing and running right. we turbo guys dont even mess with cams they do nothing for us you can gain the power in boost. so what i mean is, if you keep all your aftermarket NA stuff on there you prolly wont be able to use a premade map, and you will have ot have lots of tuning done. just fyi future headaches warning from trav.

Actually the J-spec cams are extremely good for you turbo guys as well...they allow a much better blend of torque once boost is introduced, meaning they get rid of that quick surge of torque that starts once boost is created and ends around 4500rpm...They instead allow the engine to create a much more linear torque curve, with a good bit higher peak hp output...It is easier on the gearbox internals, helps with traction, and will help with acceleration times...The torque is still there, but less peaky and maximum torque is not made quite as soon...

The torque surge is not that much of a problem for those of you with LSD's, and a lot of you probably like that neck pinning torque...but for those of you pissed about roasting one wheel all the way through first and second gear, it is a worthwhile upgrade...and will help with peak whp numbers...

 

[Matthew]

where the hell did you learn all this s***?

 

[zmepro]

right on, this is the type of info i like to hear

 

[PaulMP3]

I have also heard that NA cams are bad for turbo. It is better to get them custom ground to custom specs suitable for boost.


Good info though.

I would like to see a higher compression turbo protege, the engine mgmt is finally here to do it with.

 

[p5sundevil]

well i always refer to my favorite SCC issue which is sept of 02, it was the one with all the Bozz cars, primarily the 450hp evo VI.

With the gt3037s(a big sweet turbo for high boost 2.oL apps) and whatnot they used adjustable cam gears capable of +/- 10 degrees of change. If custom cams are bad for turbo why would they do this, they also raised the compression from stock to 8.9 to something with new pistons.

honestly that car has to be one of my fav imports ever.

 

[Installshield 2]

it is confusing to label cam profiles Turbo or NA...A properly turbocharged engine will make a similar dyno plot to it's stock NA counterpart just with the numbers reading a lot higher(that is confusing I know, the hp and torque lines on the dyno graph look the same more or less)...So adding the same set of cams to each engine will do the same to each more or less. Most cams available for obvious turbo'd engines (SR20DET) in RWD cars have large lift, and mid duration for a unbelievable punch of torque at boost...The cams will do the same without turbocharging, just not nearly as noticably...So you hear about a lot of built SR20DET's and 4G63's with torquey cams, mostly becuase they are in cars that have the drivetrain to put that power to the ground...We do not...

But the same holds true for an FS...If you would go with cams that help with high rpm breathing, and have less lowend grunt it will behave similarly between NA and Turbo...The dyno plots will look similar, with the Turbo's just being higher on the scale...

here is the catch though...If you go with too aggressive of a cam, you loose lowend torque...which in turn fizzles turbo spool immensely...This is probably what you guys heard about...Cams like this don't hurt NA engine's as much becuase there is no turbo needing spooled, and the gutted torque is made up for after the engine climbs up to around 4500rpm...A cam profiled for lowend torque will give excellent turbo spool with a tire melting torque blast just after full boost is reached...the power and torque curve will drop dramatically after that...those are the cams used in drift cars mostly...The J-spec cams fall perfectly in the middle...they realistically help high rpm, do a much better job of blending the midrange torque, and are not to big for spool-up...As long as your turbocharger's turbine is mapped properly for an FS (basically meaning as long as you have the right Turbo for your car and output) you also will not have any different spool-up than before...

 

[zmepro]

soooo, they are a good thing?

 

[Installshield 2]

soooo, they are a good thing?

refering to the J-spec cams, indeed they are...Even talk to Edwin (theMan) about this...This is probably one of the few modifications (j-spec cams with Turbo'd FS) that he won't give you s*** about...

 

[PaulMP3]

it is confusing to label cam profiles Turbo or NA...A properly turbocharged engine will make a similar dyno plot to it's stock NA counterpart just with the numbers reading a lot higher(that is confusing I know, the hp and torque lines on the dyno graph look the same more or less)...So adding the same set of cams to each engine will do the same to each more or less. Most cams available for obvious turbo'd engines (SR20DET) in RWD cars have large lift, and mid duration for a unbelievable punch of torque at boost...The cams will do the same without turbocharging, just not nearly as noticably...So you hear about a lot of built SR20DET's and 4G63's with torquey cams, mostly becuase they are in cars that have the drivetrain to put that power to the ground...We do not...

But the same holds true for an FS...If you would go with cams that help with high rpm breathing, and have less lowend grunt it will behave similarly between NA and Turbo...The dyno plots will look similar, with the Turbo's just being higher on the scale...

here is the catch though...If you go with too aggressive of a cam, you loose lowend torque...which in turn fizzles turbo spool immensely...This is probably what you guys heard about...Cams like this don't hurt NA engine's as much becuase there is no turbo needing spooled, and the gutted torque is made up for after the engine climbs up to around 4500rpm...A cam profiled for lowend torque will give excellent turbo spool with a tire melting torque blast just after full boost is reached...the power and torque curve will drop dramatically after that...those are the cams used in drift cars mostly...The J-spec cams fall perfectly in the middle...they realistically help high rpm, do a much better job of blending the midrange torque, and are not to big for spool-up...As long as your turbocharger's turbine is mapped properly for an FS (basically meaning as long as you have the right Turbo for your car and output) you also will not have any different spool-up than before...

wouldnt there be a bigger benifit to get custom cams designed for a turbocharged engine with "large lift, and mid duration for a unbelievable punch of torque at boost". Where could i find specs like these to get custom ground on blank cams

 

[Installshield 2]

It will take me a while to dig up all the specs on FS cam profiles for various applications (it is hidden deep somehere over at the Pclub)...But IMO you would be better off just staying with the stock cam profiles if you like the lowend surge...The stock cams are profile'd exactly for that, mostly becuase Mazda figured all of us wanted an Automatic transaxle and the engine needed to make the torque low to make up for the power sapped out by ATX...Theoretically you could go with torquier cam specs, but you would always have traction issues, drivetrain integrity issues, and probably WORSE acceleration...you would make good torque low, but if you are at the track or racing, the engine will be up in the higher rpm range where it will be making less hp than before...after first gear the turbo is spooled and you will always be above 3,000 rpm, in which the benefits of cams with these specs would grow thin...

 

[Matthew]

can you come over to my house and make my car go zoom?

 

[Installshield 2]

sure dude...

 

[zmepro]

(rockon) (mj) (nana)

this thread has got some really good info in it

 

[charles]

BTW, you mentioned autocrossing in the first post, if you are serious about that, you may wish to check your classing rules. Serious engine mods will probably take you out of any class where you are competitive. Then again, engine mods are fun

 

[zmepro]

haha yea, i have looked but it was too confusing and i didn't really care lol

 

[Gyre]

I thought the problem with some NA cams when going FI is that some cams have overlap, which can be good for NA but in FI can result in blow-through. That's not to say ALL cams that are good for NA would be bad for FI.