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-   -   Have Upgrades But Still Running Stock Boost: Why? (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/have-upgrades-but-still-running-stock-boost-why-657797/)

rx7 SE 05-31-07 03:18 AM

Have Upgrades But Still Running Stock Boost: Why?
 
So, I'm wondering why my car is running practically stock boost with the mods i have... they're listed below but i'll tell you them anyways. I have a cone filter with a custom 3" intake. And the only other mod that would affect boost would be my straight through 2 1/4" exhaust and straight through muffler. I've checked my turbo and it has no play. My boost gauge spikes at 6psi and works its way down from there..... any suggestions, cuz i have a friend that has the same mods but a straight through 2.5" exaust and he spikes at 10 occasionally.. Thanks!

stylEmon 05-31-07 01:38 PM

you dont want boost spikes. your engine will lean out and you'll detonate.
get a rtek ECU, up your secondaries to 720cc and get a walbro fuel pump. that'll allow you to push 8-12 psi safely.

classicauto 05-31-07 02:09 PM

2 1/4" exhaust belongs on a wastegate dump, not hanging off the back of your engine :)

Get something LARGER!

stevensimon 05-31-07 02:12 PM

80mm or go home

10thAEWHiteHeat 05-31-07 02:21 PM

its not really necessary to have an Rtek and 720's to run 10lbs.. You can do that on stock fuel no problem. Upgrade your fuel pump, but the Rtek and 720's are only a bonus and a little extra added safety that will cost you at least $5-600. First of all upgrade the size of your exhaust especially your DP and get a walbro. Then if thats not enough for you then invest in Rtek, FMIC, injectors, boost controller and all those goodies

apexFD 05-31-07 05:16 PM


Originally Posted by stevensimon (Post 6996309)
80mm or go home

+1

-Ben

stylEmon 05-31-07 05:19 PM

I'd have to disagree with you whiteHeat.
First, Rtek and 720's should only run you around $300. A Full 3" exhaust will cost more than that.

If you upgrade only the fuel pump, it may help you push a little more boost safely, but you'll be pushing 20 year old injectors... not a good idea. I;ve seen these leak from the electric connectors at top.

Best to be safe if running more than 8 psi.

Upgrading the DP is a good call tho. that stock piece is about the worst part of the stock set-up.

Juiceh 05-31-07 05:25 PM

LoL 2.25" exhaust....

MaczPayne 05-31-07 06:30 PM

Boost controller.

10thAEWHiteHeat 05-31-07 08:01 PM

well let's see... Rtek with shipping and everything will come out to at least 300, and while you spend that you might as well shell out the extra cash for the 2.0 because it is well worth it. Then injectors will run you $100 or more depending on brand and size. So you are looking at about $400 bare minimum and the arguement here is if you are gonna do something do it right. Not to mention this is assuming he does all the labor himself... A manual boost controller might be an idea also. If you are gonna stay stock turbo then you might want to port the wastegate to try and prevent boost creep if you feel up to it but this is unnssecary also just a bonus. But i feel like we are getting way ahead of ourselves here the man just simply wants a little bit more boost:bigthumb:

Sideways7 05-31-07 08:14 PM


Originally Posted by 10thAEWHiteHeat (Post 6996347)
a little extra added safety that will cost you at least $5-600.

Yes, but a rebuild motor costs $1k-2k. Which is the better deal?
Upgrading the fuel system for boost isn't "safety" its necessary. For mildly raised boost an Rtek and 720's probably aren't necessary, an upgraded pump and some type of fuel controller are. If you are cheap you can get an FD pump and a used S-AFC II, but you might as well do it right and get the r-tek.

Also, anyone who is saying get a boost controller has no idea what a boost controller does or how it works. There is NO possible way that a boost controller can lower boost. None. All it can do is raise boost. To keep boost under control and prevent boost spikes the ONLY thing you can do is port the wastegate.

rx7 SE 06-02-07 12:17 AM

ok, so what i'm getting from you guys is to increase the diameter of my exhaust (specifically downpipe) at least 80mm or greater, and also to buy an upgraded fuel pump like a walbro. Oh, and my fuel injectors only have about 10,000 miles on them along with my motor. Thanks for the replies guys.

stylEmon 06-03-07 01:18 AM

how is your motor going to be able to manage the higher flow from an upgraded fuel pump?

You injectors will still flow about the same amount of fuel even with an upgraded pump and larger dp. Will help a little.

You need larger injectors and some kinda of fuel management. Rtek is the best for the money.


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