Aftermarket intake manifold options?
 

I looked at Elite's manifold, upper and lower and those are for singles (no clearance for twins)

I have BNR twins on my car, plan to turn them up for a high boost map this fall. I am looking to improve flow and hopefully reduce manifold pressure by finding a better lower, or combo with an upper and or bigger throttle body.

I have searched the forums for results or experience with aftermarket combos like those, really haven't found anything. Especially for hybrid type twins such as the BNR's.

I guess I am trying to see if it would be worth the swap to these combos, one, 2 or all combined before I $tart ordering this stuff.

The Xcessive LIM works with twins I believe. Or you can look at the JDM RE LIM/UIM combo.

I read a 10 year old thread where the excessive LIM required port cleanup before install. I wonder if they improved the porting since then?

Also, if there is a TB bracket available for it now as well as an oil filler neck instead of modifying each of those to fit.

If anyone has an FD UIM for sale as a result of their new manifold with functioning secondary butterflies, I'm down to take it off your hands. :) Just shoot me a PM and we can work something out.

If you are running BNRs, I hope you did every other upgrade possible before thinking about a new intake/throttle body. With BNRs you are not making enough power to outperform the stock intake.

Only exception being the excessive lower intake. Which evens out the front and rear runners. But still, at 400whp, it won't matter much.

The Lower intake manifold is what I am set on buying, I was asking in addition if the TB and upper are worth it in addition.

Doubling the rear wheel horspower of what the stock manifold was designed for should make a considerably significant difference, not to mention each rotor having even flow- that should mean more power.

Have you personally seen a car that made 400rwhp not gain anymore on the dyno after retuning with the 23% more flow then excessive claims?

I'm all ears if you have.

As far as every other modification, here is my list:

Other then a new stock port motor and the restrictive Racing Beat catback I believe I have it covered, if not please tell me..

Pettit cool charge 3/intercooler
Pettit intakes
Greddy elbow/blowoff valve
block off plates
Single throttle cable
3" downpipe
3" midpipe, no cats
RP fuel pump
RP Fuel rail
550/2200 injectors
midified soleniods sequential fine tuned
3 bar map sensor
3 port modified actuator
modified lead coil
HKS Twin Power
air pump delete
Pineapple underdrive/ pulleys
Apexi Power FC
Various heat reduction protocals
Reliabilty effects

I made 351hp/294 TQ with a little heatsoak at 15 psi, this was before I added the HKS Twin Power.

Per advice from both IR performance and Banzai Racing, with the addition of a better flowing catback and the twin power- Just those two changes retuned should net me another 30+hp.

The addition of the excessive LMI will support increase flow of those larger turbine compressor wheels on the BNRs. Less backpressure= more efficient. That should mean more power.

We will be using race gas 100 octane this fall with the above listed items and will turn it up until we lose efficiency.

There will be a safe pump gas tune and the race gas tune stored in my power fc.

I have no issue with the excessive LiM as I mentioned in my post. It does improve flow.

However, it won't make much of a difference on a low horsepower car (400 or less). There is a reason full intake manifold do not exist for the fd like they do for cars like the MK4 Supra and LSX engines. You should not assume that doubling stock power of of an REW benefits from a different intake manifold/throttle body combo.

Get to 600 then maybe.

So are you saying an increase in 23% more flow requiring a retune just to run the car safely= won't make much of a difference?

If the the LIM from excessive requires a retune because of more flow, that means the addition of more fuel and timing. Does your "won't make much of a difference" mean 30hp?50hp? Especially when you have high back pressure and require AI or race gas beyond 16psi and you plan to go to 20psi.

My point I am trying make here is based on your "horsepower" figure in relation to the excessive LIMI. It's NOT the horsepower. It's the boost and the back pressure and turbo size/type.

That's why I asked you if you have a hands on experience or a link to a thread where there was little to no improvement in a situation like mine.

I am running GT28's with stock size Housings, and lowering of backpressure may be possible with increased flow from the LIM, which could allow for more efficency, lower EGT's, and more power both on my pump gas tune and race gas high boost ceiling numbers.

To me, your method of rating the manifold by 600hp and anything less meaning "not much" just doesn't "math out".
You simply cannot leave out the factory flaw the mazda LIM intake has in forcing/creating the difference in flow from front to rear rotor, and if the excessive LIM corrects that issue and ads 23% more total flow, it should be more of a difference then you are telling me.

I can agree with the upper intake and throttle body, and your take on those items makes sense to me.

More trouble than it's worth really, if you're running twins. Requires grinding clocking and modifying other parts of your piping that will shift. People are making way more power than you with twins on the stock manifold. So, it's not like you've hit the ceiling.

You made no sense man. People with large street ports and more boost, of course they will make more power. As I said, I was on pump gas, no AI, and without at least 2 supporting modifications.

So.if Balljoint, who on BNR's, made 470rwhp added the excessive manifold , would he make more hp? His twins were close to maxed out.

Again, it seems like I am receiving opinions and no apples to apples comparison or experience.

Don't be dense.

I was looking for some real world experience on these, guys who ran with them or tuned on cars who had at least the Excessive LIM in place.

I will order this LIM and see what happens on the dyno and if it changes the avg hp per lb of boost or help with manifold backpressure.

I will post up the results whatever they may be, it's 500$, see if it's worth it.

The moderators can put a "sticky" on it, or not.

If you are non-sequential it is not too bad, but if the twins are still sequential it will be a mess. There are none of the vacuum line pass-through ports, so you will running them around the LIM.

The real reason to install the Xcessive LIM is to run 4 secondary injectors. It is not just the LIM, but they have the secondary rail and oil filler neck on their site. You will be into it for $800 + fuel injectors. Be prepared to do some clean up to the casting. I have their 20B LIM, it needed a bunch of work, I actually sent the first one back to them because it was so bad.

In the end it is your car and you can do what you want with it, however your dyno results will not mean anything unless you do back to back tests - stock vs Xcessive LIM with no other changes.

I was concerned about the amount of cleanup on the ports and flange area I would have to do.

Also, sequential is manditory for me, it's really the only reason I went twins vs single.

I really don't want to change from the RP rail injector combo I have now either.

Definitely something to think about, the amount of trouble and cost vs the benefit.



Thanks for the info.

IMO, many things can be done to improve airflow and thermal efficiency in the still twin turbo setup. I am finishing a 2.5 year total rebuild of my USDM 94' Touring, I bought new in 1994. In airflow, any improvement that can decrease turbulence and preserve laminar flow is good. I used a JDM exhaust manifold, which I ported since they are oval at the engine which causes some turbulence. Also, this does not have the EGR port, which also causes some turbulence. I ported the turbo manifold for the secondary turbo to match the primary turbo opening. The door still closes and seals well. I used JDM UIM and LIM's, which were extrude honed, which increased airflow by 40% at 1 psi. This will be less at higher pressure. My throttle body was ported by RC Engineering. My engine is street ported and the intakes on the side housings were ported to match the LIM. This engine was rebuilt back in 2014 by Chris at Rotary Performance. The downpipe is a SMB with a large bellow and 3 1/2" tapering to 3". I used a Vibrant Ultra high flow racing 300 cell metal racing cat, which is OBDII emission legal in all states (no exhaust smell), and is very free flowing. I used a set of Hitachi SP High Flow turbos, I purchased from Ari at Rotary Performance, the 3KAI's with custom Forge actuators (higher spring rates) I had specially made and modified myself to fit the OEM brackets. For everything else I did on the thermal efficiency side, including complete ceramic barrier and dispersant coating, look at my posts with pictures from this other thread from a few months ago.

http://www.rx7club.com/3rd-generatio...gement-1127373

I just started the car two weeks ago and everything is working fine after a few faux pas, such as a oil leak from the oil thermostat connection and a bad coolant thermostat. The throttle body also had to be completely readjusted after porting. I am finishing up some odds and ends and will be on the road in two or three weeks. I will report back after road testing and tuning.
Mike

That is some great info Mike. Are you in the DFW area?

What do you mean by "Single throttle cable"? Double-throttle delete?
Efini 'Y' Pipe?

Double delete, how it was when I bought it. I was told there was a modification done to the throttle cable bracket too.

It has the modified Y-pipe (from BNR)since the install of the BNR turbos, it is necessary.

I am in the Huntsville, AL area. If anyone has any questions about what I have done or any advice to improve on anything, feel free to reach out to me. I restored my first car when I was 16 years old (1957 Chevy Belair 2 door Hardtop) and have worked on and modified cars for the many years that followed since I am now 59. I bought my first gen RX7 in 1980, bought my second gen in 1986, and this car in 1994. Just PM me your contact info if you want to talk or text, or simply post on this site if the info is beneficial for all.
Mike

Honestly, you can (and I have) clean up the stock ports on a LIM, its referred to as match porting against the gasket.

I think the broader point everyone is making is that the GZ LIM flows better, but if you have other flow restrictions in the system (like the TTs), you aren't going to see much out of it. There's some benefit to even flow F/R, but it's at the cost of a lot of hassle with moving your piping and lack of vacuum pass throughs, etc.

With your setup, maybe better just leave it. I'm running the stock LIM on an 8374 single setup, and it made great power.

That's from someone that actually tracks their car. Good advice.

What these senior FD owners are trying to explain to you is that the stock intake manifold(s) are not a restriction in power at the levels you're talking about. As a result, trying to run with the "bigger is better" theory won't necessarily result in linear gains. You'll need to be pushing MUCH more power before the stock UIM/LIM become a point of restriction.

About 8 years ago I sent my UIM and LIM off for extrude honing, coupled with a nice coating on the interior/exterior. At the same time I had my TB ported and enlarged butterflies installed.

If you're dying to burn some money on your intake then you could also consider that route.

It wall makes sense. Thanks.

I am trying to lower the back pressure and make these BNR twin more efficent.

Wait. You're trying to lower exhaust manifold backpressure (turbine inlet pressure) by changing the intake manifold?