downpipe
 

Got a remap on my rex about a month ago! its all straight through from the stock down pipe at the moment! would it be ok for me to fit the hks down pipe or will this cause boost creep? its mapped on a powere fc if this is any help?:scratch:

other mods?

Its also got a bigger stock mount intercooler, hks induction kit and a hks blow off valve.

i think he mainly wanted to know if you have any fuel system upgrades and did your tuner mention around what PSI you could "safely" run?

So you're not running the oem stock main catalytic converter?

and does your oem downpipe have a cat in it or is it presumably catless?

No it would be totaly catless if i put the hks downpipe on, but at the moment its running stock downpipe and straight through from there. the fuel pump has been hardwired and thats it. Just not sure if its safe to put this hks downpipe on?

Im still a noob, but id say its probably not smart on account of the possibility of boost creep. Has your wastegate been ported? and what about karack's question, at what PSI did your tuner say would be the maximum safe PSI for your car?

Then again since you are essentially running it straight through anyway, it may not make that much of a difference.

I guess the big things are whether your wastegate was ported and how much boost you can handle safely according to your tuner.

Sorry, but you're not speaking in plain english.

Trying to decipher what you said, it appears you're currently running an oem precat, then a straight midpipe (no oem main cat) then a catback exhaust.

I recommend installing the HKS downpipe, re-installing your oem main cat, and get the car re-tuned.

Search 'boost creep' to find out about the problems you'll have with low backpressure and the stock internal wastegate's inability to control boost properly.

If you have an RHD import you probably don't have a pre-cat type downpipe. I think that was only put on the US models, but then I've never been to Scotland.

You could look into getting some restrictor plates/high flow cat etc. I'm guessing you went with the midpipe and got rid of the air pump? A PFC won't prevent boost creep.

At the expense of imitating Mahjik:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/jyro-fixed-my-boost-creep-520667/

At the moment the exhaust has the stock downpipe and then a de-cat and then blitz cat back, so its all straight through from the stock down pipe! and is currently mapped for that. But im not sure if its safe to fit the hks down pipe incase i get boost creep. No the wastegate has not been ported, and im not sure what psi is safe. Some say it sould be ok since the car is mapped for being straight through but then others say the downpipe can make a difference and may cause boost creep? So i dont know if its worth the risk of trying to gain a few extra bhp or not?

save your money for a PFC and boost controller, it wont make too much a difference changing from the stock DP to an aftermarket one, maybe 1-2 bhp at best. When you get a PFC, just use that to tune how you can with the boost controller. Thats better for you in the long run.

i have a pfc, just dont have a boost controller

In our North American models MAZDA intalled a "Pre-cat" in the stock downpipe in addition to the "main cat". What Goodfella was asking was if your "stock downpipe" in RHD European models has a pre-cat. We (he and I) assume no, since it would be hard to fit around the steering linkage. If that's correct...and you have no pre-cat, do what Goodfella recommeded. Install the HKS DP with the main stock cat (or a high-flow aftermarket cat) and have it re-tuned. If not, you are risking boost creep w/o a ported wastegate.

And FWIW asianguy02, your giving advice that could cost the OP his motor. Neither a PFC or a boost controller will help with boost creep. Boost controllers are only good for controlling spike...not creep.

Another thing of note... I believe the PFC has the ability to act as a boost controller in and of itself, so as long as you're running around/under 1 bar you'll be fine, IF whoever did your mapping utilized the PFC to act as a boost controller. This will not, however, protect against boost creep (which can kill an engine just as surely as a boost spike).

Who did your mapping, if I may ask?

its a jap import so im not sure if thre is a baffle in the down pipe or not? It was mapped by pip gardner at wgt auto developments. It is just running on stock boost.

Brodie,

There is no real rhyme or reason to boost creep. Some people get it with full exhausts and some people don't. Some people can port the wastegate to solve it, for some porting doesn't help. Others may have it and just not notice it. ;) The reason on the latter is if the car is going to creep to say 13 PSI, if you always have your boost set to 13 PSI you would never know.

Honestly, you just need to monitor your car and see where you end up after each mod (especially ones around airflow).

Ah, good to hear, Pip is good and tends to know his shit iirc. Have you spoken to him about this yet? I would suggest consulting him as he's done the mapping. Personally, I was an RE:worx customer when I lived in the UK, but I was also a good bit further south then you.

Well could i try it on and if it does overboost then just put the stock one back on again? Surely cant be any harm in that can there? lol

Yes, you can. You just need to be careful is it doesn't take much to overboost and cause detonation.