2001 Coldside BRP/FFS (not sure which)

[Kyp J]

Just got back from a Dyno Day sponsored by BEGi (Bell Engineering near San Antonio) There were a lot of hot turbo Miatas, a few Mustangs, new and old some with after market Superchargers or Ford supplied which I didn't see run and a brand new Lotus (not an Elise) similar but better looking in my opinion.

The Lotus had, if I remember correctly, a peak HP of 163. The torque curve was really odd looking. It had 2 humps, the smaller first followed by a big one. Can't imagine what that would feel like on a WOT acceleration.

I don't have a file to display yet. Just a printout. It is pretty simple and looks like several I have seen here except for numbers. I may have a problem with my VVT since I have a P0012 code all the time (VVT retarded).


I have a 105 mm crank pulley, ELF and "Split Second" to control the E-Cool. Running with 93 octane and 9.1 compression pistons.

Edit: I forgot to add that I have a Goodwin midpipe for Turbo (bigger I guess) and an older Roadster Sport muffler. Pretty loud till I put in the thing in the end with a smaller hole. Dyno was without it.

My torque was a top of 132.17, HP 168.7. Torque curve virtually flat all the way with less than 5 lbs of variation (gradual crown like the cross section of a road). Several people were impressed with the torque curve. The turbo curves I saw were like the cross section of a pile of sand.

My fuel readout with a tail pipe sniffer was about 12.2 till about 3200, jumped to 13.6 and gradually lowered to 13.2 by about 4500 and almost flat all the way to 7000. Not too bad considering the ELF. I'm assuming the actual pre CAT would be a little richer or about right on except for the early richness.

[Serpico]

Hey Kyp,

I'm just curious. What happened to the 10:1 pistons? Did you do a rebuild?
I wish I had 9:1. This 10:1 is a pain in the.......

Is that CEL indicating that your VVT is not connected???? I remember reading somewhere that if you unplug the VVT, that the intake cam will go to full retard. I think I read that on Flyin Miata's web site, but I could be confused...

well, let's face it.....I am.

[Kyp J]

I had a rebuild done due to a slight oversight while in a trackday earlier this year. I failed to pay attention to the temp guage and cooked my pistons and cylinders.

Everything else was OK so I put in Wiseco 9-1 pistons and had some porting on the head done along with new valve guides. At the same time I rerouted the cooling via the thermostat at the back. A lot of jury rigging and ghetto parts to accomplish it, but it seems to work.

I only just put the belt back on after being delayed in breaking it in because I moved cross country.

Hope to be able to get some more torque by going bigger on the pulley. I'm wondering if what I achieved at the dyno would be acceptable for the equipment described. I was hoping for higher torque. Maybe VVT is pulling it down.

The VVT and all elec. plugs are connected. I took it all apart and looked at it and checked timing belt timing and everything looked clean and orderly but I have no idea if it is working right. I saw a troubleshooting procedure in a hard to read tech manual on line. I guess I will have to go back and read it more closely. It seemed to be a little complex.

[Serpico]

I checked again on Flyin Miata's web site and in their dyno section, there's a comparison run where they unplugged the VVT on an 03' and it does show a drop in torque of 5-6ft/lbs.

[Tom @ Fast Forward]

Kyp,

I would have thought closer to 190WHP with that setup? I wonder if they got the valve timing back where it belongs when they did the rebuild. Sounds like your VVT could be functional but starting from the wrong point. That could also kill your WHP.

That setup could probably support a 115mm pulley with the 9:1 pistons but you still need to check initial valve timing. I think you are off a tooth.

[Kyp J]

Kyp,

I would have thought closer to 190WHP with that setup? I wonder if they got the valve timing back where it belongs when they did the rebuild. Sounds like your VVT could be functional but starting from the wrong point. That could also kill your WHP.

That setup could probably support a 115mm pulley with the 9:1 pistons but you still need to check initial valve timing. I think you are off a tooth.

It doesn't look off a tooth to me. I set the timing of the belt. They had it off by about 90* (exhaust and intake both either fully closed or fully open on the same cylinder.) They thought it was right because they felt compression tuning it by hand. Both closed on an upstroke would be a lot of compression. If I moved it a tooth it would be way off the timing guide on the sheet metal. I have a picture somewhere of the timing before I tore it down and after I put it back and I read all the stuff I could find on belt replacement.

I just took off the valve cover and top belt cover to check it. It is right on. Unless the crank pulley is off. I couldn't see the reference mark on the block for that. Too many parts to remove. I used the front timing guage for a timing light and it was close. A tooth would put it off more than that I think.

About that, do you know of the 2 marks on the damper, which are 10 degrees apart, if the second (to arrive at the marker) is the one to align with the "T"? I think it is but would have to go back and re read all the write ups to find the info. for sure.

[Kyp J]

How much HP is 5 or 6 ft/lbs worth? Would the lower compression pistons affect the torque significantly with everything else being equal?

[Tom @ Fast Forward]

Kyp,

You know you are at top dead center when the one dot is on the zero and the other is off the damper all together. If one is on the zero and the other is on the 10, then you are at 10* before TDC. However, you also need to know if you are on the intake or exhaust stroke.

HP = Tq * RPM/5252

So, 5 ft-lbs at 1000 RPM = 5 *1000/5252 or about 1 HP. 5 ft-lbs at 5252 RPM = % * 5252/5252 or about 5 HP.

The 94-97 would make less WHP with the same identical setup (pulley ratio). However, it can make more in the long run as you can run larger pulley ratios without ping. Ping, even the stuff the knock sensor pulls out that you never hear, causes the ECU to pull timing to compensate. The low compression allows more boost without ping. So more timing means more HP to a certain extent. I think the rule of thumb is around 1.5 WHP loss per degree of timing pulled. Drop 10* to cure ping and lose 15WHP.

[Kyp J]

I believe it was at the top of the compression stroke getting ready for the power stroke. Approximately when the spark would happen is when most TDC and timing mark coincidence happens.

So you are not sure how much less the 94-97 (are they the ones at 9-1 compression or are they 1.6L?) would be with the same pulley? Do the hotside and coldside with the same pulleys produce about equal torque results?

With the sllick pavement here, even dry, and the LSD, it is hard to keep the back end behind the front as it is now.

Another possibility that I have to think about before spending more money, is oil pressure. It can cause problems with the oil control valve on the VVT. I installed an analog sender when I reinstalled the engine but haven't calibrated the needle on the guage. It reads low as it is. I need to re read the procedure in the garage section of M.net to see if it is comparable to other's experience. Or: go by a complete guage and stick it on temporarily. Hard to get to the sender with SC manifold on. any other spots to tap into oil pressure?

[Tom @ Fast Forward]

I believe the 94-95 are 8.8:1 and 96-97 are 9:1. they typically run 5mm more pulley to match the WHP-Tq of the 99+. With the same BTB, the coldside will make ~1.5-2 PSI more and ~5 WHP more than a hotside.

[Kyp J]

OK I am going to try to post a scanned image of the dyno graph I got back in my original post. It has both runs which are very close.

It didn't work. File size was 209+K and limit is 19K. Oh well.

[Tom @ Fast Forward]

Convert it to a JPEG and lower the resolution. For some reason JPEG file size is set to 100K.

[Kyp J]

Where is the VVT shift supposed to appear? This came out a bit small after Tom fixed it. The jpg file was almost 1 meg in size but when attached, it was only 17K. Too much work to get things in here for a retard like me.

[Tom @ Fast Forward]

Actually, the VVT in the Miata is different from the variable cam system in the Hondas and other cars. It is continuous. I believe it is load based.