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-   3rd Generation Specific (1993-2002) (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/)
-   -   External Wastegate on Stock Twins. For those who said it can't be done (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/external-wastegate-stock-twins-those-who-said-cant-done-1000553/)

Mps_hell 05-27-13 01:51 PM

Wasn't ment to sound that way. Not dissin your work I think it's very good and will save money, I just couldn't see why you said they couldn't be sequential anymore after this mod. Sounded like if I was to proform this I had to go non sequential. Also there is more to this mod then just holding more then 18 psi. Cheap Dead internal wast gate repair. I like to try and keep my car as "stock"as I can if I can kill off the internal east gate and still stay sequential I will more than likely have a crack at it

Ball joint 05-27-13 04:48 PM


Originally Posted by Mps_hell (Post 11479032)
Wasn't ment to sound that way. Not dissin your work I think it's very good and will save money, I just couldn't see why you said they couldn't be sequential anymore after this mod. Sounded like if I was to proform this I had to go non sequential. Also there is more to this mod then just holding more then 18 psi. Cheap Dead internal wast gate repair. I like to try and keep my car as "stock"as I can if I can kill off the internal east gate and still stay sequential I will more than likely have a crack at it

It's all good and thanks for the compliments, I guess I took it the wrong way as well.

After thinking about, you might be able to do it, but you would have to remove the pre-spool actuator door and you could keep the main door in place that diverts most of the exhaust to the front turbo. Problem would be that without the pre-spool actuator and assembly in place you would have a longer transition between both turbos having full boost. It's a very interesting idea I'm going to have to think about.

cptpain 05-27-13 05:24 PM


Originally Posted by Ball joint (Post 11478967)
I don't have a graph from this run but I do have a graph from when I made 470whp 400tq on a dynapak two weeks ago. Just for clarification the prior BNR non-sequential record was set on a Dynapak at 425whp. On this graph/run I had ignition breakup at high RPM due to me getting greedy with spark plug gap. I regaped my plugs before I made the run you see in the video above which solved the problem as you can see.

https://i.imgur.com/fdTOwwgl.jpg



I chose to go non-sequential because the flapper doors limit the maximum power that can be made on the twins. The whole point of this build is to see how much power can be made using the stock frame turbos and using every exploit possible to extract that power.

As for "all you did really was port out a hole that was already there and blow a hole in a plate yes?" I think this doesn't give credence to the amount of time, work, and planning that went into doing this. This mod is something that has been talked about on this forum for over ten years with no one finding out a way to do it. Without this mod you cannot hold more then 18psi to redline and if you're running a wide open 3" exhaust you will also be dealing with boost creep problems at around 15psi.

If you don't understand the work that was done above then either you didn't read what I wrote, or you haven't been around the RX-7 world long enough do understand the problems that this fixes and the potential for more power it brings.

Thats a nice graph. Very progresssive.

What do you use the car for if I may ask; Drag, Road Course etc etc?

Mps_hell 05-27-13 06:18 PM

I have doubts to whether or not the pre spool door is needed on the stock system at all, well at lest on my s8 1st turbo is spooling from the Minute the car is started and all the boost is getting dumped till the stock valve closes . That doesn't seem to be till 2600rpm. Might be something messed up in my car

Ball joint 05-27-13 07:51 PM


Originally Posted by cptpain (Post 11479181)
Thats a nice graph. Very progresssive.

What do you use the car for if I may ask; Drag, Road Course etc etc?

Thanks for the compliments! It's one of the reasons's why I've always liked non-sequential twins, the lag is really bad, but the power is delivered very progressively which allows for the car to have full traction in third gear. I've been in single turbo car's that make less power but rip tire in third because of how the power comes on all within 500rpm. Second gear is still usable but it rips the tires loose pretty bad.

I use the car primarily as just a street car as it's more a experiment for me. I like pushing limits and doing what others say can't be done. Currently this setup is not viable long term as I'm sure my exhaust manifold absolute pressures are through the roof! That's why the torque is so high.

I still want to try to hit 500whp on the twins, might blow the motor trying, but knowing it can be done is worth it.

OverEzzz 05-28-13 03:14 PM

I would love to see this mod in a more detailed how-to guide. Good luck in hitting 500.

Lock & Load 05-31-13 03:18 AM

Great effort keep us posted :icon_tup:

FD_virus85 05-31-13 04:43 AM

"the lag is really bad, but the power is delivered very progressively which allows for the car to have full traction in third gear"

That was my two weeks thoughts since i got the non -bnr 3's, lag is there but it's much better power delivery, power comes just enough for high RPM's to take care the rest of the power
on the sequential twins at third gear my car squeeks then gets the traction after (short period of sudden power then just dies off)

Even for track u get better corner on these u get to really step on it like non turbo LOL when i had sequential twins every corner i had to worry about sudden power delivery... somewhere in my mind
Also u don't hear your bov million times when driving long period of time XXXX these bov kicking on me everytime u let go the gas you wanna plug your ears after 3 hours of driving, on these non-s bnr's at second gear u gotta really step on it to hear your bov!!

I have some questions..
How are the lags and power deliver after all the work, respect on the numbers and work!

cloead 07-16-13 07:33 AM

THIS IS SOME CRAZY STUFFc

Grant M 07-23-13 11:44 PM

Any results on this yet?

edgars95rx7 08-06-13 01:12 AM

You are my hero ball joint. great job on the mod

Grant M 03-19-16 01:16 PM

Did you ever make 500hp?

Ball joint 09-03-16 06:05 PM


Originally Posted by Grant M (Post 12041171)
Did you ever make 500hp?

No, never had the will to push it that far as the EGT's are high and I set the record; so I was planning on finally going single. That was until some Australian's decided that BNR's are crap and they can do better with hybrid twins. So I guess I'm in a new dick measuring contest.

Zepticon 09-03-16 07:28 PM


Originally Posted by Ball joint (Post 12103186)
No, never had the will to push it that far as the EGT's are high and I set the record; so I was planning on finally going single. That was until some Australian's decided that BNR's are crap and they can do better with hybrid twins. So I guess I'm in a new dick measuring contest.

Only guy i have seen dissing the BNRs are the guy selling what he calls SP twins that he says he developed together with Hitachi?

DC5Daniel 09-03-16 08:18 PM


Originally Posted by Zepticon
Only guy i have seen dissing the BNRs are the guy selling what he calls SP twins that he says he developed together with Hitachi?

Ding ding ding

Zepticon 09-04-16 02:14 PM


Originally Posted by DC5Daniel (Post 12103211)
Ding ding ding

I think that if you have to talk down a competitors (very good) product to be able to make your own look good, you dont have much of a product yourself. I was considering getting the SP twins, but when i asked about them i got a lot of hubris, which does not convince me. So im going with BNRs when i get to that :)

Flybye 09-13-16 07:13 PM

Buy old manifolds, modify, make a group buy, just sayin. ;)

Anyways nice job!

kensin 10-17-16 06:59 AM

I'll send you my manifold and money lol

Fritz Flynn 10-17-16 12:13 PM

I love the innovation :)

However IMO you just ruined the only two advantages (internal wastegate and sequential) the twins have LOL

Wouldn't a t78 make about the same power with a similar curve at 15 to 17 psi?

borisf 10-17-16 03:48 PM

This is great. What size wastegates did you end up using? (sorry if i missed it).

I ran an External Gate on m 05 STi many years ago and yes, although it was loud (didnt have it plumbed back in the exhaust), the power delivery and boost control/ was much much better. Thats on one puny sized turbo.

The install is definitely not without its challenges from the pics, but still awesome work.

SakeBomb Garage 11-04-16 03:46 PM


Originally Posted by Fritz Flynn (Post 12115973)
I love the innovation :)

However IMO you just ruined the only two advantages (internal wastegate and sequential) the twins have LOL

Wouldn't a t78 make about the same power with a similar curve at 15 to 17 psi?

When I first read the thread I was hoping it would be a solution for an external gate on sequential twins. Non-Sec twins have all of the disadvantages (IMO) of sequential twins (huge lump of glowing iron on the side of the motor and compromised exhaust flow paths) and few advantages besides cost. It's cool to see someone innovating though! :icon_tup:

RX7Zamboni 11-05-16 12:45 AM

Someone's gata figure out how to do this but stay sequential

Flybye 11-05-16 05:39 AM

Hey BJ, have you ever compared the 280hp fd exhaust manifold with the older ones to see if the potential for more flow is there?


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