To DP or not to DP, that is the question!
 

I've read everything I can on and off the forum re DP's. So I understand basically how they work and the benefits of less restricion, less heat, etc. Some retailers/mfgr's claim as much as a 25-35 hp gain. I know how those claims go but I'd be happy with half that. However, my car is used for street use only and I live in an urban area where I rarely get to rev it real high. What I don't know is whether the hp gains will be accross the power band, or mainly at higher rpms? If it will have a dramatic effect on 0-30, or even 0-60 times I'm game, but if it will only benefit me in a quarter mile, I'll pass. Any advice will be appreciated.

You will definitely notice a difference, my primary turbo spooled a bit earlier after I installed the downpipe. But the foremost reason to get a DP is the heat reduction under the hood, you prolong the life of everything under there by reducing the heat it receives.

Matt
93 SSM

Exactly, I was more worried about the heat rather then hp gains.

Another vote for a DP as a reliability mod rather than just performance. But the performance will also be helped dramatically. :D

same here that dam thing puts some heat out for sure:( Get a DP now before it makes things worse.


-Ryan

only problem with a downpipe is the potential for boost spikes :(

O.K. I won't argue the benefits of reducing all that heat. That seems to be a foregone conclusion and reason enough to add a DP. But I'd still like to know what to expect in performance gains.

you'll start engaging the clutch at a little higher rpm to get the same feel as before. You'll notice a slight drop in response at the low rpm range when you hit the gas while underway. The difference, however, is very small, and hardly noticeable.

I too drive my car conservatively and was a bit bummed when I first drove the car until I felt the passenger's side fender after a long drive and was actually able to hold my hand on it. not to mention that there's a much more noticeable power change in the upper rpm range that's fun to venture into every now and then.

According to your mod list you already have a catback and intake. Before you do another exhaust mod you really should upgrade the ECU, get a standalone unit, or control your boost somehow. With a DP, CB, and intake you are definitely going to see some elevated boost.

Thanks. You anticipated my next question!

you don't need a dp, just punch out your precat :)

DP, CB and Intake will be ok on the stock ecu - as long as you are running the STOCK cat you should not get any boost creep or spikes.

Check my sig I run all my mods on the stock ecu and have no boost spiking or creep issues - and the black soot in my tail pipes confirms what my A/F meter is telling me - I am still running rich enough.

a DP will drasticaly reduce underhood temps even more so if you wrap it with ThermoTec as I have.

Yeah, do you feel that your footwell is really warm now? The stock precat tends to clog up a lot too causing extreme heat conditions. Once i got rid of my precat, that extra heat in the footwell was gone. I felt a little bit of extra power, but my main concern was just heat reduction. It'll increase the life of your engine, your turbos, and everything else. Might as well get it and be on the safe side :)

its not even about the power gain only. its about less heat. your underhood temperatures go down significantly. and thats good for the operation of the car. heat is rx7s biggest enemy. if you can get something for 300-350 bucks that can reduce this problem, then why not?????

To DP is the answer. all the way!!!!

This is my "Before" Dyno chart :
http://www.rx7.bnis.net.au/images/Twin/S7_Dyno_1.JPG

And here is the "After".
http://www.rx7.bnis.net.au/images/Twin/S7_Dyno_2.JPG
(which actually shows before and after anyway.

Everything else is stock. (note KW, not HP) :)

Whats the conversion from kw to hp again?

thanks.. :)

You took the words right out of my mouth! Thanks gotorrx7, a pic is worth a thousand words. Now if I only new the conversion for kph!

100 Kw = 98.63 Hp
100 km/hr = 62.14 mi/hr

nope

100 kW = 134 HP

140 kW = 188 HP - very low for stock FD

152 kW = 203 HP - represents gain of 15 RWHP

what does kw stand for?

my pre cat got clogged and i started to notice a loss in power, so dave at kdr put a downpipe on for me. If your pre-cat was clogged you will notice a big difference in the power. As far as heat goes, I could always hear my cars exhuast system make noises after i shut the car off while it was cooling down. After the downpipe i dont hear these sounds anymore.

My precat was in great condition and when I put in a DP, I noticed big difference throughout the powerband, especially in low RPM. I was really pleasantly surprised that I would gain performance in low rev. I thought it was just for high RPM.

It's gotta be one of the best things you can do to get better performance and not sacrifice reliability.

was it the dinging noise?

http://home.c2i.net/valhovd/images/Arild/P1010065.JPG


Must be your tractor leaning out in third.....

Yeah, thats what i thought the conversion was, but i thought something was wrong with my calculation when i found 188hp at the wheels on a stock fd.. that IS pretty low for a stock fd.. :(