Sorry - my original post was deleted as I didn't understand the buttons!!
Dear BLiNK,
It was me who was, and still is interested in your kit. I'm sorry if I sounded disrespectful, that wasn't the objective. If we didn't understand and respect your history on racing and engine building, we wouldn't even bother discussing about the kit. Again, apologies.
For a start, let's forget the bhp, hp and hub hp figures. Say B6 engine produces 100 power. We know that you can get up to 10 % more by usual enhancements, such as intake, exhaust and timing. After that you normally need Money (or FI). This information is collected from dozens of dyno runs with different (mx-5) cars and dynos.
What we have experienced is that by increasing the compression ratio, overbore, head porting, race cams w/ adjustable cam gears and fully tuned megasquirt can finally give you up to 25-35 % more power. But as said, you need a little bit more than a valve job and good wash for that.
Could you please explain little bit more accurately what the head and cams go through in your hands. I'm quite sure it won't ruin your business, we don't have enough market or makers to copy, we would be glad to use your service if the results are what they are told.
Cheers,
Antsa
Hi Antsa,
Thanks for the very polite reply - I do wish we could speak the native language - it has taken me 15 minutes to log in to the forum!
In respect to the cylinder head there is various internet rumours in respect to how certain Miata Cylinder Heads flow better than others (i.e. a 1999 Head is supposed to be the best) - we have tested the various heads and there is in fact very little difference between them even though the ports on the later heads are higher.
When 'Porting' a cylinder head you have to look at where the major restriction to airflow is within that head and this will always be the valve & valve seat itself.
If you 'break the cylinder head down' it consists of the Port, then the Bowl, valve seat, valve itself then lastly the chamber.
For example, if the port is capable of flowing 400cfm and the valve seat 300 cfm; no matter how nice you make that port the head is still only capable of flowing 300cfm.
The Ports on all Miata engines are already extremely good but are slightly oversized for standard Normally aspirated use (They were originally designed for turbo application in the 323) so when a company actually ports your cylinder head and makes it all nice and shiny they are actually loosing performance because the Port velocity falls - the Port velocity is the most critical performance component and not the actual CFM figure.
To improve the Miata cylinder head (and every other cylinder head produced) you must first improve the valve seat and valve itself. The early 1600 cylinder head does not have a three angle valve seat. The industry standard thee angle seat is 30/45/60 degrees - our flow bench tests again shows this hurts performance. Hours spent testing on the flow bench has found seat angles that flow the best (we will not disclose these!). We also modify the valves themselves and enlarge the seat as far as possible. The angles on the exhaust and inlet valve seats should be different to prevent reversion of the gasses.
Testing a cylinder head on our digital flow bench:
Results: (Comparison between a 1993 & VVT Head:
Once the valve and seat area has been addressed the next biggest restriction is 1cm above and below the valve seat. De-shrouding of the valve area in the combustion chamber significantly increases the flow of the head and once this is done the port velocity increases to its optimum - any further porting will reduce the performance of the cylinder head.
The above modifications aren't just cutting valve seats but give you 95% of the total performance available from the Cylinder Head - only an extremely experienced head porter will gain anything over the standard Miata design!
David Vizard (world renowned cylinder head specialist) was given a Miata cylinder Head to examine and even he said he could not improve on the original design!
Further Reading:
http://www.eurospares.com/graphics/engine/Vizard/Porting%20School%20%235%20Identifying%20Primary%20Restrictions%20-%20GoFastNews.com%20-%20All%20Racing%20News%20All%20the%20Time!.pdfOnce the cylinder head flow has been optimized the next reason the engine performs poorly as standard is it's low compression - remember it was originally a turbocharged engine hence the 9.4:1 standard ratio.
Through our experience of racing we know what compression ratio these engines like and we choose an improved ratio for the engine. High compression pistons are expensive and the ones available are very poorly designed! They do increase the compression ratio but have a protrusion out of the top of them which affects the cylinder burn and the power - a flat top design is the preference.
We gain the compression by re-facing the cylinder head.
The camshaft grind we choose is still quite mild to help low down torque - if they were fitted to a standard cylinder head the low down torque would be less but because of the improvements in the cylinder head breathing at the lower valve lifts low RPM torque is maintained. The higher compression, Megasquirt and the cam profile increase the Higher RPM Power.
The Megasquirt is the Keystone of the package and is responsible for a significant performance gain - it really doe open up the package and users know this well.
Along with the AFM delete kit (Contrary to popular belief it is not the AFM that causes the major restriction in the inlet but is the air box itself!) The kit combines nicely.
I have put links in the previous post - please feel free to contact the people who have purchased these items to get their views directly without any interference from us.
We hope the above helps a little bit - to finish here is the power plot from the first 1800 kit we did:
