This actually looks very similar to the 2.0L BP non-stroker I built a while back... I used 11.5:1 85.5 pistons in my build though.

I disassembled your motor and sonic checked it - it would have punched a hole in #3 in short order. ;) Who built that engine?

https://www.miataturbo.net/attachmen...ine=1329031190
https://www.miataturbo.net/attachmen...ine=1329031190

I'll answer that for Urban. Dave at Builtmore in Los Angeles built it. His shop "specalized" in subaru's. I had to get mildly aggressive with him to get my stuff back from him. I started a thread on NASIOC trying to resolve it peacefully, and a guy from his home town posted up a bleak portrayal of his honesty, which I'll second.
/hijack

If anyone wants some 11.5:1 85.5mm supertechs pm me :)
//hijack

That looks fun as shiat!

1) Intercooler reduces airflow to radiator

2) Thick walls on turbo manifold conduct heat back into head - not sure how much effect overall this has on engine temps tho

I sent my 97 M3 cams to www.elgincams.com and he custom ground them for not much money (IIRC ~$350). 4-cylinder miata cams should be cheaper.

The same dip at 3250 for stock cams. It's at half of the power peak RPM. That it's at 3700 tells you the cams/IM are tuned for higher RPMs.

You are doing the exact opposite of what my critics are telling me to do with the steering wheel. What gives?

Hooking thumbs in?

What, pray tell?

The tell me one steering-input, "be smooth", and blah blah blah. I'd rather listen to you than just about anyone else.

Look how slow he's moving the wheel, no real huge jerks, smooth as she gets I'd say.

To stay in PTC, I had to remove the bump steer shims we ran in PTD. That makes the wheel jump around more over bumps. Necessary evil to get the ride height we want. If you look at the net steering input for most turns, minus bump steer kick back and corrections for slides, it is fairly slow. Transitions from left to right in esses but that's to be expected.

I don't focus, or even think about any particular steering method. I just try to give the car the input that it wants. If the car turns in well, only a little steering input is needed with a fast entry and a whisker of trail braking. That should translate to the needed steering angle for the mean arc you are describing through the turn. That is what they mean about one input. Some drivers will go in too slow and deep, then over brake and dial in a bunch of steering to get the car pointed towards the apex. The harder they go in and more abruptly they release the brakes, the more the car gets upset and requires a quick opposite lock correction right at turn in. This just kills speed in a Miata.

You have posted videos here before but I don't know where to look. Link to post so I can see what you're doing.

edit:
The car was not completely dialed. New spring rates, alignment, spoiler, pad compounds, splitter, wing, tires on their last legs. Car was close but not balanced exactly the way I like so I was perhaps making more corrections than usual.

So is the OGK NA chassis done for?

This car looks fantastic. Paving the way.

I know I need to "turn-in once" rather than chop-down on steering-angle. I'm on very old tires here too. Rip it apart please, have fun.

Hustler watching your video, I have a suggestion.

don't hook your thumb around the steering wheel. if you w2w, have a contact. it could break your thumb. It has happened to someone I know pretty well.

I'm aware after watching this video, I also grip the wheel way too hard. I started hooking my thumbs because I am so weak in my teres major/minor, infraspinitus fascia, and serratus posterior. I do not have the strength to turn the wheel for a session without hooking my thumbs. I'm spending an additional day in the gym every week solely working one these muscle groups for next month. I've spent the past six months really trying to get stronger.

Thanks for the advice.

The chop down turn in is just not being confident. That the car is actually changing direction when you do that means the tires don't already have a lot of slip angle which means you're going in a bit too too slow anyway. Got work up to a slightly higher entry speed so that it's sliding a bit. Some of that is bump steer and 9's catching rough pavement. I'm doing a bit of that in my car too.

Watched a few YT videos on MSR-H CCW from several drivers. On this particular track, not that you asked:

T1. You and everyone else turn in too soon and too slowly. Should be later and more abrupt almost where the tire barrier starts. If you're not nipping over the entry kerb on the right, you're not far enough to the right. It should also be a lift, turn in, straighten slightly then brake in a straighter line then finishing by trail braking into the right just a wee bit.

T2 It's so long that I would hug the inside more and give it a burst of throttle mid turn. Lining up the exit is nice but it's easy to waste a bunch of time camping out for the eternally long 11s to line up the exit.

T7 I would not late apex that either. You go from 120 in the straight, down to 90 or so for the turn then park it at 45mph for the bus stop. No matter what you do, the exit of bust stop is a 48mph 85° turn. Running up the inside of 8 won't change that. If I were racing you, I'd dive up the inside and my lap time would not change.

Entering 7, I would make a diagonal from right left edge to brake later and in a straighter line, finishing by trail braking a bit into the turn. reminds of the old turn before the pits at SMMP.
The very beginning and end of this lap, the fast 90° right just before the pit entrance. http://youtu.be/AorNENnwJNM Same basic idea but applied to your T7.

T8-9. I think I would use more of the kerbs.

T10-17
Nice line through all that.

.02

The original NA chassis used for the OGK will become a very low cost E3 car using up a bunch of spares we have laying around the shop.

Talked with Andrew for a long while last night. He would not let me rationalize keeping this a BP4W head. He's right and I know it. Gotta be a VVT head. This BP4W head is such a work of art though. It's just sorta old school to me now without VVT.

The SU/ITE car will be and NB with F/I. The remainder of the plan is TBD.

Thanks on all of that. Some of what you recommend is less scary, I like that. I need to work on a few things, one I just added to the list is "how to turn the wheel faster, with grip." I think your advice in 8, while eating up the curb, will buy me a lot of time on that corner alone.

Hopefully now that I have data I'll learn something new.

Thanks for that write-up.

I am very tempted to do something similar on the SAAB/Miata, likely minus the VVT head. The more I read the more excited I get.

Perhaps I missed it in another thread, but why the RB header? What happened to your super badass argon back filled header? Wasn't it called the Laguna?

The RB and Squaretop are most probably not the designed pieces, they might just be what was closest at hand. The Squaretop might be OEM due to rules but the RB header would not be hard to beat at these levels.
Why wait for a new header (sold out, on another car, ...) when you have something that works and it's close to raceday/dyno time?
Even Emilio is human I guess. :)

Got a message from my cam grinder, identical profile on IN/EX,
10.7mm max lift
1.27 mm 250 °
1.00 mm 256 °
0.30 mm 302 °

It will a bit too extreme with Squaretop+RB, but I don't plan to use them forever :)
Oh, and the blanks from Mazda did not have enough material on them for the profile without going down to 33mm base circle (my plan was 34mm from the start). The max lift was no problem though. The lifter pockets might not need modification after all.

Emilio, Sav,

What percentage of blocks have you sonic checked, have enough meat for the 85.5 pistons?

After watching it again, I saw something else. T8 is very off camber. Generally, in off camber turns you want to take a tight line and spend less time turning. The reason is the g load is much lower. So an autocrosss style flick and snap rotate is the ticket there.

Conversely, the apex and exit of 9 has quite a bit of positive camber. Watching G trace form your video and a few others, I see that people aren't hitting the exit of 9 hard and rotating enough there. Average G's should be higher than the other flat turns but I'm not seeing it on the videos with data. When you have a "pocket" like the on at 9, you attack it with a steep fast entry and crank in steering right at the apex to snap the car into a faster yaw rate. At the apex you would want to see a brief plateaur of G maybe .2 higher than the average elsewhere.

None of that is huge but maybe worth .2s combined.

Emilio, wunderbar! Just waiting eagerly to see VVT gloria to arrive...

I had a VVT head that I considered installing. Looking at my AIM data the revs never dropped below 5k. All of the VVT dynos I have seen show no benefit above 5k. Now I don't know what that extra 1mm of lift from the VVT cams get you but you seem to have that covered.

I would be interested in buying the current BP4W head for my car if you ever want to sell it.

Thanks man, great advice, it makes sense.

Enquiring minds want to know!

Anyone who claims to have this data is a bold-faced liar with absolutely no knowledge of the basic rules of statistical analysis. You would have to sonic check hundreds and hundreds of blocks to determine the percentage of BP blocks that can safely take 85.5 slugs - and even if you were to waste a year or two doing that, you could never safely base any engine building decision on that analysis, because even if 60 or 70% of BPs can safely take 85.5s, that means you have a 3 in 10 chance of grenading a $3000+ bottom end because you weren't smart enough to sonic check YOUR block.

We'll build 85.5mm bottom ends upon request, but the sonic testing that is REQUIRED to run those slugs will cost you extra.

I've had these cams for a few years now.

.427 cam lift intake, 272°
.410 cam lift ex, 266°

Clearances are bigger than OEM so actual lift is less of course. That's about the most duration I would run in an engine expected to idle. A VVT head might tolerate another 5-10° since you can dial out some overlap at idle and IVC doesn't really affect idle vacuum.

So these are really midrange cams. Even with IRTB's I would expect peak power to occur around 7700 and roll off to about 8400. Peak torque will still be in the 6100rpm range I think. Our hybrid manifold will still retain the same runner length as OEM so we should have even more area under the torque curve. There are Miata race cams out there over .500 lift and 310° seat duration.

Problem is now that we're already past the power cap for our class so there is no point in looking for more power until the car is retired from PTC in April. That's when the new car will debut. At that point we can resume the path to 200whp. A VVT head would simply have more torque down low and idle better. Neither of which matter for an F/I race motor. For a street motor however, it makes sense to start and high compression N/A project with a BP6D head like our 95R street car.

Do you have .050" duration numbers for that cam? Advertised numbers leave us to a lot of guessing. Lift seems pretty stout.

Nope, sorry.

No problem.

I would like to ask you another technical question. What was involved with the crank scrapers? Does the crank lightening allow you to get the scrapers closer to the crank?

I want to put scrapers on my next motor, but I do not know how well they will work with those damn casting ridges on the crank throws. It seems like a waste without them gone.

Pricey?

Actually late IVC does reduce idle vacuum, but with small overlap the idle will be smooth. </nitpick>

Neither one of us asked for statistical analysis. We asked for your experience.

I have 6 blocks bored and honed and sitting in my buddy's garage waiting for assembly, and all of them sonic checked fine. I presume that you've build a great deal more 85.5mm engines than the 6 blocks I have had close contact with, and I'm curious if it's common to have a run that long check out at .1" over the stock bore, or if these blocks are as bad as, say VG30DETT blocks, with which you might only have 1 in 5 blocks check out thick enough to punch 2mm over.

Actually some data is better than no data (e.g. "out of 5 blocks we sonic tested, 2 had enough meat"), to give some idea of how hard it is to find a block with enough meat. Nobody is suggesting to skip the sonic check.

Fair enough. I've only checked one engine and it failed, so my experience hasn't been particularly good. ;)

http://www.crank-scrapers.com/

The ones in my engines are custom made by my engine builder, not by the company in the link above.

Is 11:1 better than 9.5:1 for E85 use? I’m building forged engine (for F/I) and wonder If I should go with 11:1 Supertechs. I’m only using E85 and its quality stuff here in Finland. 106octaine 80-85% all year round

+1 on ^ ? I already have an 11:1 motor laying around, been wondering about the very same question, (what with e85 a mile away)

I wonder what CR the ST 11:1 actually will give on a undecked block since the compression height seams to be lower than stock (at least mine were). With some unshrouding maybe 10.5 or even slightly less. That's if the domes actually are 10.5cc on them.

Yeah, mine are 84mm, I know, but there might be the same design practice on the 85.5.

E85 is magic stuff. All of you E85 guys if you could start over again, would choose 11:1 pistons?

I did E85 test 6 months ago with my old supercharged stock 8.8:1 motor. I didn’t have FMIC only Aquamist WI
- Cut the water injection off and start pushing the car.
- After 15min hard street driving I didn’t hear or log any knock (I had det-cans)
- I add more timing until around 22 deg btdc finally engine starts pinging. And that was with 14PSI boost
[/cool story bro...]

That clears up my understanding on the way they work. I thought they scraped a portion of the side of the throw as well, but I see in the pic that they scrape only the furthest point from the center axis of the crank shaft.

I was dreading the installation, but now it looks much easier.

Thank you.

Any idea the cam timing in these?

Any plans to sell similar cams in the future?

That's depends on your goals and I'm probably not the guy to ask. Personally, I'm a response -----. I dread a turbo system with any lag whatsoever. I'd simply don't enjoy driving a car with bad control feedback and non-linearity, even if it's fast. So for me, I'll set up the car to have as little hysteresis in TPS/Torque as possible. One of the means to that end is high static compression and E85. Others running big turbos and a ton of boost might be happier with less static compression. Sav is better versed in the pros/cons of that decision.\

Bottom line is with E85, I can so I will.

No.

No lobe center info was supplied. It's up to me to mess with them on the dyno and see what works. I don't know where they are at now, only that the indexes are zeroed out.

I run 22* @ 20psi with no pinging and no WI. :p

Yeah, but with IC ;) I didn't have any (coldside SC)

an idiot that isnt around anymore.

N N N HDJJSJEIE. SNUFGLE S

Valuabe contribution

This means that you should not care about the guy who built the motor - he is out of the picture for good. Guy has completely disappeared. Meaning, I know of at least 5 people who have been actively trying to find him for well over 2 years.