arildh

Have you observed any gains with the square top and a bigger TB ? It is pretty much 2.5" from inside the flange to the runners. A 65mm TB + 2.5" piping must be good for something @ 9K.
Edelbrock Mustang TB hackjob:

speedingbolt

iTrader: (1)

Emillo your pretty close I picked up a used Maxim with the flex pipe cut off for the price of an obx header last year. I have to try and get it modified to either fit like a stock header or just make a custom exhaust setup. Either way I'll end up spending abut the same amount of money. It'll just take alot more time to use the Maxim.

If you compare a Murha and a Maxim the primaries and secondaies are the same dimeter the collector is larger 60mm and the routing of the pipes are nearly the same its just got the 50mm venturi and split construction that really distinguish it from the Maxim.

My class doesn't allow as much modification as what you are doing with your engines I have to have a stock long block or at least one built within the guidelines of the factory manual and a stock intake and throttle body and this is why I kinda of think that the Maxim might be more optimum for my application. If I was running an elevated redline and making more power I wouldn't hesitate to get the RB. I guess I was just looking to see if anyone else might agree that having higher exhaust velocity due to a smaller collector and catback would be more optimum for my more limited level of prep.

emilio700

iTrader: (3)

You and I know that.

We tested on a bone stock longblock, not a high RPM race engine. You have already convinced yourself the MW will be "better" based on conjecture. Run it


I assume your question is "have you observed any gains with the square top after adding a bigger TB ?

Nope. Above about 170whp we could just barely see a repeatable 2whp at very high rpm. That's an annoying A/B/A test. Do the math on flow. Stock TB flows enough for about 250whp N/A. F/I is a different matter and we have done no testing with TB's there at all. The math indicates there will start to be gains above 250whp F/I with a bigger TB. So test it and report back if you would please

my97miata

What about a VVT engine with stock cams, +1mm valves all around and a thin head gasket, is that an interference engine too?

emilio700

iTrader: (3)

Probably not but that is the sort of question you ask your engine builder not someone on a forum. Anytime you raise the compression or change camshaft dimensions you should clay it.

emilio700

iTrader: (3)

Our shfancy 2.0L build has seen several delays. The last was a machine shop accidentally removing some of the head coatings. Fun stuff. Anyway, it's back on track and we're told the long block will finally arrive here next week.

Anyway, I wanted to repost this dyno plot of Crushers 2013 nationals motor done back in September 2013. For reference, this was done with 1861cc and 10.4:1 compression, no coatings.

More details in this thread https://www.miataturbo.net/race-prep...7/#post1049820

TurboTim

iTrader: (9)

Emilio's drunk.

hornetball

iTrader: (4)

Drunk with powah!!

emilio700

iTrader: (3)

Motor arrived a few days ago. Finally got around to taking (bad) pictures.
We have had some change of plans for our project cars so this engine may end up going into a different car. Maybe the 95R? It could really use a dry sump or at least a vacuum pump but I wanted to build something that was a bit more within the reach of the average Miata enthusiast. Thus the wet sump. Dry sumps start at around $2500 and are not street car friendly.

13.0:1
1952cc
Coated chambers, exhaust ports and valves
.450 lift cams
+2mm CNC head

It will burn E85, run on an MS3Pro with sequential fuel and spark as well as individual cylinder trim for fuel/spark. 36T wheel

We anticipate it will just touch 200whp with a square top, which hasn't been done AFAIK. 215whp or so with the same ITB's we ran at 2013 NASA nationals. We made 191whp then on 1861cc 10.2:1 bottom end, no coatings and smaller cams.

soviet

iTrader: (10)

Thats so hot

Fireindc

iTrader: (13)

pimpy. In for some videos of whatever this goes into.

sixshooter

iTrader: (12)

That's almost as much CR as people run on circle track small block Chevys that came to market in 1955. I'm saying without any real knowledge about what I am talking about (other than knowing people who race) that I think there might be even more room for growth. If you are on race fuel, why not push for a 14 or 15 CR?

emilio700

iTrader: (3)

Because we already had some custom 12.0:1 JEs sitting on the shelf. We were shooting for 14:1 this is as much as we could get from these pistons. This engine will run on E85

Gryff

iTrader: (6)

I'll take six!

Out of curiosity, which itb's were you using at nationals?

emilio700

iTrader: (3)

TWM 45's. Really needs 50's but like the pistons, its what we have laying around.

robertcope

Would definitely cheat on the wife with that motor.

robert

k24madness

iTrader: (6)

I could suggest a good Rotrex car to install it in.

TurboTim

iTrader: (9)

Very nice.

But why would a dry sump not be street car friendly?

shlammed

iTrader: (8)

Nice setup.

Similar to the engine package I plan to put together for my Miata.

Though I wont be using coatings and I don't know what I'm doing with valves or cams yet. I will be using a custom intake manifold design that will be dyno optimized for power band... not ITB's.

emilio700

iTrader: (3)

Packaging, cost. Oil tank is usually 18-22" tall x 6" diameter. Engine is built differently from the start. In my view, dry sump is sort of the last step in an N/A build to a full race only engine. If I were doing a dry sump, it would have .500 lift cams and 15:1 CR. But I have no use for such an grenade engine.

This engine was built with the intention of being used on the street. Thus, only .450 lift, way less duration than even a 185whp EP engine uses, wet sump. As mentioned before, the dry sump is a significant barrier to entry for most builders both from implementation and cost perspectives. Only a handful of shops around the country that know their way around a Miata dry sump (Prather, ARE, et,al). You would have to pay those guys to get your system right, or gamble with a $15k race motor. We always want the projects we do to have some real world relevance, trickle down the tech. 200whp with semi streetable cams and a wet sump. Possible..

EP dry sump