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New BNR twins/Dyno

Old 05-26-18, 06:45 PM
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New BNR twins/Dyno

So I had my car in the shop for the install and tune. I planned for a pump gas tune, then a high boost reace gas tune.

The car has motor from Pettit Racing, maybe 1500 miles(from what I was told after I contacted Pettit to get their involvement in the history of this car),naturally I assumed it was street ported, as Cam explained it had one of "their" balanced versions installed. Looking at the 6k rpm drop of torque on the dyno sheet, you can tell it has stock ports.
Supporting mods>

Pettit cool charge 3
Pettit Cold air intake/heat sheild
DP
No cats
res mid pipe
RB dual outlet muffler
RP high performance fuel pump
RP Fuel rail
500/2200 injectors
PFC Apexi
3 bar map sensor
Stock coils (modified lead input by Rotary performance)

High boost tune was done using 3 gallons of 110 octane on top of 1 gallon(est) of 93 pump.

Tuning had to stop at 15.95 psi because we figured out the stock boost solenoid woildn't allow for usable boost beyond that, and I needed to get my car out to the body shop, so we plan to tune higher boost at a later date. That said, the avg hp per lb of boost was 11.5hp. Seems pretty low to me, and so does the dyno HP reading.

(15.95 psi)
351hp std scale
293tq std scale
110 octane race gas
Af 11.0 to 11.5 max


I have read threads where people are getting the same power (dynojet or simular) with 13 psi.

Can anyone see anything on my mod list that could be holding it back so much?

IR performance, who were awesome with getting me these things quickly and tech support pointed out the stock coils and Racing Beat muffler as two areas of holding back some horsepower.

I was hoping for 375 @14-15 psi , and into the 400's on high boost+ race gas.
I also realize that the car with BNR's I am comparing to since he was on this same dyno at the same shop was Goodfella back when he had these twins, had an ignition amp and basically only the crank pully(no accessories) being driven by the belt, and of course, his aggressive street porting. I only have removed the air pump.

So maybe I am expecting too much? I read of people making what mine did on stock twins at the same PSI.



Dyno sheet on link below

https://cimg9.ibsrv.net/gimg/www.rx7...aa8b7290e5.jpg

Last edited by zx1441; 05-26-18 at 07:11 PM.
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Old 05-27-18, 07:13 PM
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Yeah at 6k RPM the power just goes flat. I would be suspicous of old coils or maybe look at doing a twin power. Or the Sake Bomb ignition setup.

The RB duals are on the restrictive side but it's hard to say if that's what is choking it down. Might be worth seeing if you can borrow a more free flowing exhaust from someone and see if that wakes up the top end.

350hp is still a lot of power! That should be DAMN fun on the street!

Dale
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Old 05-27-18, 07:21 PM
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Thanks for replying. By comparing other dyno sheets with these twins, I looked at the torque mine made(294) and it seems consistent with cars that made 375hp or more. Hard to believe a muffler can hold it back more the 2-4 hp when the rest of the exhuast system is free of restriction. I am considering a twin power becuase i still want the wastespark.
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Old 05-27-18, 10:05 PM
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Old 05-27-18, 10:08 PM
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We basically made the same peak power, but my peak torque is quite a bit higher, this is why I feel i am being held back at the high rpms, even though I have stock ports, my dyno was at 15psi.https://cimg5.ibsrv.net/gimg/www.rx7...833df925eb.jpg
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Old 05-28-18, 01:54 AM
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His graph is in SAE, it’ll be a little higher in STD, which is what yours is measure in.

Your number do look a little low for BNR, FWIW my stock twins made 355/308 at 1bar with stock port.
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Old 05-29-18, 04:34 AM
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https://cimg2.ibsrv.net/gimg/www.rx7...19e6a59837.png
https://cimg3.ibsrv.net/gimg/www.rx7...a25ce4b95c.jpg
Hard to believe a muffler can hold it back more the 2-4 hp when the rest of the exhuast system is free of restriction.
Unbolt the Racing Beat cat back next time you dyno.
I think you will find its more of a 10-20rwhp at your power level compared to a decent flowing cat back.
The damn thing has a 90 degree bend into a 90 degree bend the other way right before the muffler with flange mis-match further disrupting flow in the middle. Look at flow modeling for an S bend, its a terrible choke point.


Banzai Racing has dyno tuned many FDs and has mentioned in several posts how restrictive the Racing Beat cat back is compared to others.

Last edited by BLUE TII; 05-29-18 at 12:37 PM.
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Old 06-05-18, 05:53 PM
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Originally Posted by BLUE TII View Post
https://cimg2.ibsrv.net/gimg/www.rx7...19e6a59837.png
https://cimg3.ibsrv.net/gimg/www.rx7...a25ce4b95c.jpg


Unbolt the Racing Beat cat back next time you dyno.
I think you will find its more of a 10-20rwhp at your power level compared to a decent flowing cat back.
The damn thing has a 90 degree bend into a 90 degree bend the other way right before the muffler with flange mis-match further disrupting flow in the middle. Look at flow modeling for an S bend, its a terrible choke point.


Banzai Racing has dyno tuned many FDs and has mentioned in several posts how restrictive the Racing Beat cat back is compared to others.
I am considering the HKS high power, unless anyone knows of a better single straight through exhuast I should consider, but the question I have is to leave the silencer in or take it out? I would think that leaving it in, looking at the size of the hole (looks to be around 2") would be a restriction.

If I am dumping my Racing Beat dual, I want it to be worth it.
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Old 06-05-18, 06:40 PM
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There are quiet exhausts that do not require the bolt in silencer and so will flow more in quiet mode.

Apex'i Noir
Apex'i Hybrid Megaphone Evo
Apex'i RS Evo for more flow (bigger piping)

Greddy CS-GTS

HKS Super Turbo

Tanabe Medalion Touring

OBX-R (Korean knock off) more flow (bigger piping)

Basically, any cat back for the FD with a big oval muffler as above will be quieter than anything with a round cannister style "racing" muffler like the HKS High Power you mentioned.
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Old 08-11-18, 07:41 PM
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Originally Posted by DaleClark View Post
Yeah at 6k RPM the power just goes flat. I would be suspicous of old coils or maybe look at doing a twin power. Or the Sake Bomb ignition setup.

The RB duals are on the restrictive side but it's hard to say if that's what is choking it down. Might be worth seeing if you can borrow a more free flowing exhaust from someone and see if that wakes up the top end.

350hp is still a lot of power! That should be DAMN fun on the street!

Dale
not trying to put bnrs higlow twins down , but the reason bnrs twins go flat at 6k rpm is that the std compressor covers are too small in A/R

you will find if you reduce the boost the peak power rpm will go up

Itís like trying to get more flow through a injector by increasing the static fuel pressure , it will only create more heat .

so the solution is u need Bathurst sp twins they have much larger compressor covers for more flow at higher boost levels .


Designed and made by Hitachi Japan and were exclusive to the 1995 rx7 sp race car only ,and won the bathursts 12 hour race in Australia in 1995 .





.


Last edited by THE DOCTOR; 08-11-18 at 09:25 PM.
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Old 08-12-18, 12:26 AM
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TheDoctor, I read where the Bathurst SP's made 345rwhp @ 15 psi , my dyno shows 351 @ 15 psi with BNR twins, held back by 2 issues at the time of tuning(though you picked up 53 more hp at 18ost) That's more the 17hp per pound of boost. If legit, that is huge.

I just added the HKS twin power to my coils and I really have to pay attention now when my BNR's hit boost, it get's into the rev limiter alot now. Really smoothed my idle and part throttle driving out.

My guess now is part of that drop and less then smooth line on my dyno graph were the coils not having enough power. The other big factor, which I intend to change soon is my catback. As stated in previous replies, my RB exhuast system with it's 2 "S" bends and missmatched flange are also a problem.

Dyno will be in about 1 month or so, cooler weather.

Also, another thing is the solenoid and actuator combination was limiting anything beyond 15psi (and could even been less effective even at 15psi at holding the backpressure).

Here is the diagram and fix people here in the states are using with the BNR's beyond 15+ PSI....https://cimg4.ibsrv.net/gimg/www.rx7...0528dc4bc8.png
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Old 08-12-18, 06:13 AM
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It seems u have no idea , First the Bathurst sp production car which was sold to the public used the std ht10 model twins and std exhaust system and only the triple Bathurst SP race had the special larger twins which were making lot more than 345hp

second hks twin power unit throw it in the bin it does nothing , I run my oem igniter and coils and leads at 26,5psi at 8000rom with no problems .



Third your bnrs are not new there overhaul oem used ht10 , ht12 Twins that will have cracks in the turbine housings and have Garrett cores which most likely will fail very quickly. On the circuit .

I would suggest fix your exhaust system so it flows and get yourself a set HKS 50003-M45RE M-Series iridium spark plugs .

nJust trying to help u bud , but I guess you will learn the costly way , good luck .

Last edited by THE DOCTOR; 08-12-18 at 06:29 AM.
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Old 08-12-18, 07:41 AM
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https://cimg3.ibsrv.net/gimg/www.rx7...8f1804bae0.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...b2714109b1.jpg
Just so you know, my tuner (with 3 decades of experience) inspected the set of BNR modified HT12's (they are not HT10's, haven't seen a set of those in Texas yet), my set had no cracks, especially compared to the set we pulled off of my motor, which were cracked and had bad shaft play.

Second thing, HKS twin power is a temporary fix as I was getting some break up at high rpm.

Bonzai Racing and others have back to back dyno sheets showing 15-25hp gains or recovery from the HKS ign amp, we will see if mine helped when we dyno and tune again.

As for me having no idea, this is where I got my information from about the Bathurst SP twins you tuned on the dyno making around the same hp as what mine made at the same 15 psi.



https://cimg0.ibsrv.net/gimg/www.rx7...053b85a8c9.jpg

Last edited by zx1441; 08-12-18 at 08:24 AM.
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Old 08-12-18, 07:49 AM
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The HKS twin power is an effective ignition amplifier, that does an incredible job. It is a shame that HKS discontinued it. Dyno runs before and after HKS twin power install https://www.rx7club.com/3rd-generati...rison-1103125/

Do not waste your money on HKS spark plugs. There are NGK and Denso plugs that are perfect for your application should you need them.
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Old 08-13-18, 10:14 AM
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The HKS plugs that came in a JDM motor set that i got said NGK on the sides of them...

http://i130.photobucket.com/albums/p...psc0b70bb6.jpg

Last edited by Gilgamesh; 08-13-18 at 10:25 AM.
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Old 08-17-18, 06:37 PM
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Originally Posted by THE DOCTOR View Post
second hks twin power unit throw it in the bin it does nothing , I run my oem igniter and coils and leads at 26,5psi at 8000rom with no problems .

Third your bnrs are not new there overhaul oem used ht10 , ht12 Twins that will have cracks in the turbine housings and have Garrett cores which most likely will fail very quickly. On the circuit .

nJust trying to help u bud , but I guess you will learn the costly way , good luck .
DOC,
I don't know what your issue is, but it is not good form to bash other vendors and insult members.

2nd, spreading disinformation does not help anyone and only makes you look bad.

The Twin Power has been proven time and again to add power with back to back dyno runs.

Your claim of stock coils at some ridiculous boost and rpm is bogus, and in your typical form has no proof to back it up.

Lastly, pay the fee to be a VENDOR on this forum if you are going to keep trying to sell your super special turbos.

Vince
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Old 07-04-19, 12:34 AM
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Originally Posted by THE DOCTOR View Post

It seems u have no idea , First the Bathurst sp production car which was sold to the public used the std ht10 model twins and std exhaust system and only the triple Bathurst SP race had the special larger twins which were making lot more than 345hp

second hks twin power unit throw it in the bin it does nothing , I run my oem igniter and coils and leads at 26,5psi at 8000rom with no problems .



Third your bnrs are not new there overhaul oem used ht10 , ht12 Twins that will have cracks in the turbine housings and have Garrett cores which most likely will fail very quickly. On the circuit .

I would suggest fix your exhaust system so it flows and get yourself a set HKS 50003-M45RE M-Series iridium spark plugs .

nJust trying to help u bud , but I guess you will learn the costly way , good luck .
You have no idea what you are talking about.
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Old 07-04-19, 01:30 AM
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Originally Posted by zx1441 View Post
I was hoping for 375 @14-15 psi , and into the 400's on high boost+ race gas...
So did you ever get this resolved? I'm very curious on what was the root cause of your lower than expect power output. Personally, I'm skeptical that it was/is the racing beat exhaust.
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Old 07-12-19, 12:31 AM
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Odd. I have a virtually identical set of engine modifications and made 375 RWHP @ 15 psi and stock ports on SBG's axle hub dyno.

BNR stage 3 turbos set up sequentially
Pettit CC3 IC
Apexi intake
FFE step up kit with stock primaries and ID2000 secondaries
Supra fuel pump
AEM water/meth kit
SBG coils
downpipe
resonated midpipe
Racing Beat single tip exhaust
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Old 07-12-19, 06:54 PM
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Originally Posted by celkc View Post
Odd. I have a virtually identical set of engine modifications and made 375 RWHP @ 15 psi and stock ports on SBG's axle hub dyno.

BNR stage 3 turbos set up sequentially
Pettit CC3 IC
Apexi intake
FFE step up kit with stock primaries and ID2000 secondaries
Supra fuel pump
AEM water/meth kit
SBG coils
downpipe
resonated midpipe
Racing Beat single tip exhaust
Honestly, those numbers are pretty close (350 vs 375). It could be any number of external factors, or some minor setup variance or tune. And, dynos are a tuning instrument. Trap times are the truth.
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Old 07-13-19, 01:48 AM
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^ Yeah I misread his numbers, thought he was putting down 293 RWHP. 350 is within the error bounds, esp. given the stock coils.
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