[solved] Only 120 hp after tune - looking for some help
 

I've got a 1999 ST5 car. I'd like to make about 160 hp, naturally aspirated. I thought I had the right combination of bolt ons to get to at least 140 hp, but it only dyno's at 120.

Please help me find the missing power. What am I doing wrong?

Specs:
BP4W rebuilt by me (could be part of the problem) - recent cold compression test (187, 182, 190, 170) - all valve clearances recently checked
Racing Beat Header - this is getting ceramic coated
Springfield dyno inspired exhaust
22" intake runner with k&n cone filter - adding an airbox to shield it from the headers - tuning shop found 5 hp by just adding a cardboard shield to the engine bay
skunk2 intake manifold
MS3PNP
Innovative wideband

I'm attaching my logs from a recent race, and my current tune. I had it dyno tuned by a shop. Before the ecu, tune, and intake manifold, it made 116 hp/116 torque. After tune and intake manifold, it makes 120 hp/109 torque.

Can I get any more hp through tuning? Do I need to aggressively deck the cylinder head? After that, do I chase power through the valvetrain or pistons? I'd like to do this as efficiently as possible.

Thanks! This forum is awesome.

I'd say something's wrong. You've got decent compression, but that's about 5-7 degrees more advance than I'd typically run. I may not be getting all of the power out of my naturally aspirated builds, but I also get 135hp out of bone stock junkyard VVTs and stock headers. A now illegal Spec Miata head, RB header, and nothing nearly as loud as your springfield dyno exhaust netted me 148hp. That was a VICs intake manifold too. What was your break-in procedure and how does your oil look?

Same dyno? Both runs weather corrected?
Did you touch the timing belt at all?

Are you running stock cam gears or are they adjustable???

Curly, thanks for the reference data. It's been years since I broke in the motor. If I remember correctly, I did a series of 2nd gear pulls. The oil has the occasional metal shavings. I had a hard time sealing up the head gasket, after the initial build, so I went with an MLS and added ARP head studs.

The 116 hp dyno run was in Houston, the 120 hp run was in Cresson. I'm not sure about weather correction. I'm running stock cam gears. The timing belt was refreshed during the rebuild, and I'm fairly certain that it's correctly installed. I checked again when I did my valve clearances over the winter.

So, aside from just swapping in a junkyard VVT, what can be done? Could there be power loss in the bottom end? Do I need to pull it apart and blueprint/balance it? Maybe my timing belt is incorrectly installed.

I'm all ears. I've got a few months until the next race, so I've got some time. Thanks.

you have something out of time I bet. that is a really crappy number for your mod list. balance is not the culprit here.

What kind of dyno? (Im assuming dynojet since youre doing it for classification, but just checking)
Definitely double check mechanical timing and base ignition timing.

Also, do you have a copy of the dyno chart? What RPM did it make peak power, and how high did the dyno operator take it?

$20 says you mis-timed the belt

Thanks for all the feedback. I'm definitely going to verify my timing, again. I found this wild dude on YouTube that has a good walk through. It sounds like I'm off a tooth on my intake cam.


Here's my latest dyno. This is with the intake manifold and current tune.

https://cimg3.ibsrv.net/gimg/www.mia...f8402ac43c.jpg

You don’t even make 120! Your sorta make 115 and then at the end it coughs and sputters out an extra 5hp briefly.

That flat hp curve is indicative of...something. Either a major restriction, or really crappy timing.

Yup! That's why I was asking about the timing belt being done. Highly suspect.

Very well. I'll update this thread, after I've fixed the timing. It's gonna be a few weeks.

In the meantime, I'm doing a ton of research on EFI tuning and the Megasquirt system. I'm sure this is going to require some new tuning, once timing is fixed. It's going to be difficult to get it back to the tuning shop before my next race.

Thanks again for everyone's input. This has been very helpful. Running at 20:1 power to weight in a 14:1 class has been brutal :)

Ding ding ding. Ya'll were right. The intake cam was at least one tooth advanced. I wasn't able to start her up and test yet, but I'm sure proper cam timing will help :)

Thanks for all your help. I'll follow-up with new dyno charts in about a month.

One tooth advanced is a lot of overlap.

Minor update: I indexed the crank damper and found that it had slipped a notch. This may explain the tuner's high timing advance. Not knowing that the damper had slipped, I dialed in an 8 degree offset. Now I've created new marks on the damper that correspond to TDC.

I hope to test start this weekend, then find some time on a dyno before my next race, in June.

If the timing marks on your damper are moving then I'd think it was actually failing and not just slipping. Might be liable to fly off especially in a track environment.

oh no! I’ll start shopping. Thoughts on the ATI with 32 point wheel? It seems like that’s the one to get, but there are a few alternatives floating around.

Either that or Fluidampr is a bit more affordable and I think easier to install. Not sure on availability though.

Any updates on this? Just curious about the dampers really...

Yeah don’t run a slipping damper. I had one fly off once

Yea, quick update. I don't have a bad damper, I'm just dumb. The leftmost notch on the nb1 damper should be at the T mark at TDC. Am I right?

When I originally posted this, I thought the mark on the left was supposed to be on the 10, and the mark on the right at the T.

I got the car started, heard a little knock, and shut it down. I think it's the timing belt backing plate. I'll tear it back down and figure it out.

Yes, left notch goes to the T. You are not the first to have done this.

TL;DR, she purrs like a kitten.

So, I got in there and found that the intake cam gear had been reinstalled incorrectly. The guide pin (dot) on the cam shaft had shifted out of place, so when I torqued down the cam gear, it was crooked and resulted in slightly incorrect cam timing. I got that sorted out, and re-verified everything.

I got her started, and the engine sounds great! By far the best sounding idle since I've been working on the car. So, I think we've got the basic mechanical issues solved.

I've got an appointment to have the car tuned, at the end of the month. Then my next race on June 8th. I'll report my numbers, as soon as I have them.

Huge thanks to everyone for your help!

Here's the final update. Jesse found a ton of power. 163 peak hp and a steady 130ish torque through the entire range! I can't wait to go try it out at Hallett!

Thanks again for everyone's help. I couldn't do it without you.

https://cimg3.ibsrv.net/gimg/www.mia...cc1855761d.jpg
new dyno

Noice!

Dont listen to people when they say cam timing won’t make power.

Quick double take. If the timing is locked at 10BTDC...then the left notch should be at the 10, and the right notch at the T, correct?

At 10, yes but not at TDC

This is interesting. I have been battling a similar issue with my car. I have a vvt swap, skunk2 intake manifold, miataturbo 3d printed intake, jr header and a 2.5 inch exhaust and I can only manage the exact same curve that you did. It's frightening how similar our curves are. I will be investigating my car either tonight or tomorrow for a misaligned tooth somewhere. Here is my chart for comparison. Blue was with the stock catback exhaust and red was with my 2.5 catback.


https://cimg0.ibsrv.net/gimg/www.mia...75d9cdb9af.png

My N/A VVT car makes 130wtq/160whp on E85 which is more like E75 most of the time. About three months ago I went to dyno tune it and discovered I was down on power. Turns out I was off a tooth at the crank but my dumb ass mis-diagnosed it to be off a tooth at the intake cam so I moved just that. Went back to the dyno and pretty much the same results although not identical. Took off all the covers and damper to make absolutely sure and found my mistake. Went back to dyno and had 130/160 like usual.

In either case, the power loss was about 10wtq/15whp PEAK, at worst. Under the curve numbers fluctuated to even at low rpms and close to 20tq/hp at 7800 rev limiter. Amazingly enough this was the second time this happened. It was about 5 years ago the first time it happened but I wasn't the dumb ass who did the belt that time. In any case, same amount of power loss.

How the OP picked up the power he did by just cam timing does not jive with my results of being *one* tooth off. Mind you, one tooth off at the crank, or one tooth off at one of the cams is what my experience has been, twice. I was nowhere near 40hp down. I would say he had to be more than one tooth off. Or the tune was really bad. Or both.

I'm just sharing my experience so you don't think that the OP's results are what you should expect from a timing belt snafu. I don't mean any slight or doubt to the OP's results. I just don't think they are typical.

I started taking my engine apart. I can always use an extra set of eyes but it looks to me that my timing belt is installed correctly and nothing appears to be jumped which makes things seem weirder for me. What do you guys think?

https://cimg2.ibsrv.net/gimg/www.mia...613958cb3.jpeg
https://cimg3.ibsrv.net/gimg/www.mia...6a7b06d64.jpeg
https://cimg4.ibsrv.net/gimg/www.mia...11323a7f3.jpeg
T

To be sure you need to look at the timing belt crank pulley (behind the damper pulley) and make sure the arrow on it is aligned. Checking the damper timing marks will give you a false positive if the damper has slipped.

Another option is to take the #1 spark plug out, drop a long screwdriver down into it, and watch it while turning the crank pulley. Finding TDC that way is fairly simple -- not quite as accurate as using the arrow, but plenty good enough to check for 1 tooth off. I do this because I have an ATI damper and it's a PITA to remove.

--Ian

I took my pulley off last night and tdc on the pulley lined up with the arrow mark on the crank gears.

https://cimg4.ibsrv.net/gimg/www.mia...89bce1f1c9.png
https://cimg5.ibsrv.net/gimg/www.mia...c2e8c3838f.png
I realized one of my earlier photos had the cams off 180 degrees. Here are the follow up photos with my crank rotated 360 degrees.

https://cimg5.ibsrv.net/gimg/www.mia...a18cbc5c8.jpeg
https://cimg6.ibsrv.net/gimg/www.mia...1e03915a2.jpeg



It all seems odd to me. It looks like it is all timed correctly but my dyno follows the exact same curve that the OP had and he had his timing off. I verified crank trigger offset and it was spot on to give me 10 degrees actual when I commanded 10 degrees.
Attached is the ignition table I used for the red line and the vvt table I used.


and below is a quick video I took of the play my timing belt had which seemed to be a bit excessive to me. Don’t know if that could be the issue either.

Last picture with the FM tool:
Intake cam needs to be rotated counterclockwise one tooth and the exhaust cam needs to be rotated clockwise one tooth.

That is also what I see from that picture.

So this is weird because this is the oem timing belt on the engine and it previously was making 150whp in this configuration with vtekkiller. How would it jump like this? I have yet to take it off.

https://m.media-amazon.com/images/M/...14,317_AL_.jpg

I hope the crank mark is lined up better than the cams are.

Crank was lined up perfectly but I’ll snag a photo of that when I get home tonight.

You need to get the camera down lower to be sure. If you're not looking at it straight on, then the parallax error makes it really hard to tell if it's right.

--Ian

https://cimg4.ibsrv.net/gimg/www.mia...ddd664de8.jpeg


This can't be right.

Sorry, late to the party, and I never took the time to look at the posts below the pic..

I don't know much about ignition timing on a VVT engine but it looks like you are leaving a lot on the table with your spark map.
I go into 40+ below the 100 kpa threshold.

It can.

I'm not really loving the slack or the lack of straight up mark on the intake cam though. Don't remember if that's a VVT thing or not, i try to avoid those motors.

https://cimg5.ibsrv.net/gimg/www.mia...671673c4b.jpeg
https://cimg9.ibsrv.net/gimg/www.mia...f5a94f15f.jpeg

Yep, still off. Those notches are supposed to line up with the bottom of the tool. That's why there is a bottom of the tool there.

.... No..... that's in time. You can't physically put the tool low enough between the gears to get it to the marks on the timing plate.

Yeah, it looks right to me, assuming that the tensioner has been released and the motor spun around a couple times (if it were a new timing belt install).

--Ian

It has. I'd venture to guess multiple millions of revolutions.

You guys are right. I was fixated on the tool. This site does that to me.

To note, the FM tool does not work well with the VVT motor. When the tool is in place, the intake cam will want to snap back clockwise once it is free. If you time the motor like this, by the time you re-tension the belt & turn it around a couple times, the teeth will be off. You basically have to time the intake one tooth retarded then check it post-tensioning to confirm that the engine is timed properly.

Ask me how I know!!! :facepalm:

The problem isn't with the FM tool. What's going on is that if you leave equal amounts of slack on both sides of the belt, when the tensioner takes it up it will effectively shorten the belt on the intake side relative to the exhaust side and stuff will be off. You need to put it on with as much of the slack on the intake side as you can get -- this is true no matter what method you use to keep stuff aligned while installing the belt.

--Ian

I've been kind of lethargic lately working on my car but I finished up my timing belt job. I timed it exactly as it should and I made a new mark to correspond to the vvt gear in a completely vertical position to match the exhaust gear. I also tensioned the belt correctly. The car is back together and started right up. Unfortunately, I don't have any data to post yet but I did note that my crank trigger offset changed again not that the car is all back together and the current crank trigger offset to get a fixed 10 degrees to an actual 10 degrees is 0 degrees in either direction.

OP chiming in. Unfortunately, I can barely work on my own engine, much less a VVT. I definitely recommend indexing tdc at the crank, and verifying with the screwdriver in cylinder 1 trick. Follow factory instructions, and any supplemental miata forum instructions for the timing belt install. turn it over a few times to make sure it stays in spec. Get a good dyno tune, with the new configuration.

As for my big bump in power, I'm fairly certain that the exhaust was off too, and I've added the mazdaspeed intake cam while I was doing the work. The head was decked during the initial rebuild. I too was surprised by the dyno results.

Again, big thanks to the forum. sixshooter and friends have been a big help.

I don’t know what did it but I replaced the belt and miscellaneous seals. With the new belt properly tensioned and me playing with street tuning some more I managed to get this dyno plot.

https://cimg6.ibsrv.net/gimg/www.mia...d4eb619bd.jpeg

That's right in line with what an untouched VVT engine on a stock header, K&N intake, and any sort of aftermarket exhaust should do. Some optimization of the I/H/E and either bowl or compression bumps can get you around 150hp. Emilio claims that 150hp number with an untouched VVT and I/H/E, but that's still the entire Racing Beat catalog, a really nice VVT motor, and a really good tune. I haven't been able to breach high 140s with that setup, Emilio's saying 150s possible, but that's splitting hairs at that point.

I hear that the nb2 header is pretty efficient at doing exhaust things. I am running a JR header which at its smallest size after the collector seems to be somewhere between 1.75 and 2 inches in diameter. Also my cat is a magnaflow which is only 2 inches on interior diameter. I am sure that those two variables contribute to me not make what Emilio with the whole RB catalogue makes. My goal right now is to maximize my toque and see if I can get closer to 120/125 torque and call it a day for naturally aspirated stuff.

A large portion of my HP gains seems to be from adding more vvt from 6k and up.

The blue line was using this new VVT table and red line was running I think the tune I had before the belt was changed. But before the belt was changed my dyno plots seemed rather non-responsive to vvt changes.

https://cimg0.ibsrv.net/gimg/www.mia...02ac0d7600.png





https://cimg8.ibsrv.net/gimg/www.mia...e68b4a75c.jpeg

This is correct. Thanks!

RE: VVT advance,

That's really odd that you're gaining power from adding advance up top. Most maps I've seen make max hp with close to full retard on the intake cam up there.

Andy, ​​​​​you are very close to my virtual dyno chart, VVT + Boltons and a squaretop. I was expecting a bit more but I expect I will need to pay for a dyno tune for that. I should just boost my damn car already.
https://cimg3.ibsrv.net/gimg/www.mia...f96bc60d77.jpg

I think there is something not quite right with the VD graphs you guys have provided. I have about 200 dyno runs and have seen countless other N/A unmolested VVT engine dynos and all of them ramp down and stay ramping down once they pass the 6K mark on the torque side. Both of those graphs have the torque regaining momentum. That's not right.

I think it's time for both of you guys to hit an actual dyno and get real results. If your tune is anywhere near decent, your engine is in proper working order, and your engine ancillaries are not choking it, you should be seeing 120 wtq and 130 whp on an unmolested VVT engine on gasoline. With a good tune, a square top with a good air intake, a long tube header with a free flowing exhaust, you should get 125 wtq and 145 whp on gasoline.

I believe both of you will be pleasantly surprised by actual dyno results. The torque numbers on your VD are way low in my experience.

https://cimg0.ibsrv.net/gimg/www.mia...1aff540d2.jpeg

It seems like my 134 run was a false positive. I did some extensive testing last night adding and removing ignition timing and adding and removing vvt timing. All my tests were 3rd gear, roughly the same time on the same road.Blue line here was with the same ignition and vvt table as my previous best run. I have to double-check that my afr table was exactly the same too, I just realized I might have changed that. The blue run here was me adding more advance to igntion timing. Adding or removing timing in either vvt or ignition reduced my vd plot.

Edit: Double checked, appears to be the same afr table.

What does your timing table look like? Here's my timing and intake table. No advance before 3k RPM as my advance at 1600 rpm caused the car to buck around that RPM Range.

https://cimg4.ibsrv.net/gimg/www.mia...380042c805.jpg


https://cimg7.ibsrv.net/gimg/www.mia...7ee791690a.jpg