I've lost almost 20 RWHP- help!

[bmattick]

About nine months ago I installed an OBD2 intake/cam kit from Turner Motorsports. I was very pleased with the power increase (+37 RWHP), driveability and feel of the kit.

I money shifted the car this summer and ended up having the head rebuilt. The rebuild included all new valves and valve guides. Expecting that the new head would add (or take away) a few HP, I took my car to Edge Motorpsorts for their dyno day the other weekend. The results were shocking- I went from 243 RWHP to 225 RWHP!

So now I'm in a bind, I've lost half of the power I gained from the kit. What I can't figure out is what would have caused this power loss. The schrick cams were re-installed and indexed according to the cam install spec, which is a BMW AG document. The software (JC) was never touched. The onlyt modification to my car in the interim was to install 18" BBS rims.

I've eliminated dyno disparity (?) as a cause. All 3 dyno runs were on a dynojet, 2 at DSR and 1 at edge. Many customer have dynoed at both places and seen minimal difference. 20 RWHP is too huge to just be the difference there.

Any ideas what else I can check? I need that 20 HP back!

[Balthazarr]

Don't know, maybe the wheels?

that is a lot to lose from just that change tho.

[RRSperry]

Same dyno? Same operator? Who did the engine work? Are the cams and the VANOS correctly timed? Did you notice a loss of percieved power before the dyno run? Way too many variables here...

[aeryk7]

A crappy rebuild could have been the case. Have you done a compression test lately.

[bmattick]

I should add that the car feels great, it never entered my mind that the rebuild was poorly done. I can do a compression test etc, but the real question is how can I resolve this? the shop that did the work is sympathetic, and will likely make things right, provided I can figure out what the cuase is.

[dshilkit]

I should add that the car feels great, it never entered my mind that the rebuild was poorly done. I can do a compression test etc, but the real question is how can I resolve this? the shop that did the work is sympathetic, and will likely make things right, provided I can figure out what the cuase is.

why do you need to do the troubleshooting? they did the work -- perhaps they should be looking for answers. we'll likely only be able to speculate about possibilities...

[Mad Dog 20/20]

That sucks. Sorry to hear it.

I'd say its the cam install, especially if a different tech/shop put them in before. i know many people say that the install is "easy", but i disagree. The "proper" timing is key. My tech (BMW race motor guru numero uno) did not time my Schrick's to OE specs (intentionally). I think there is some "wiggle room" in there that can make a big difference, depending on how its done. A poor cam install can cost you big power. A "nice" install can maximize power.

Also, please post the dyno.

[mmaigret]

Garrett,

Any idea what specs your mechanic _did_ time the Schricks to? I have a lot of experience playing around with timing Schricks and my instincts tell me that the OE specs should work pretty well. Did you mechanic retard the exhaust cam? I have found that this helps with mid-range torque. Any information you have or could get would be interesting to me.

Thanks,
Mike

[RRSperry]

Again, what makes you think it's the car and not the dyno?

[nightkrawler]

this stuff is way out of my league but let me ask you a question. even before you took the car to get dyno'd. did you feel a loss of power? 20hp to the wheels would definately be noticeable. how does the car feel? does the butt dyno say it's slower?

[Serious]

how many times did you get 245 dyno'd???

what other mods do you have?

[GGray]

I have been through M3 hell this summer...BUT to make it short here is what I did/found...

After putting my car back together and taking it for a drive it was CONSIDEABLY faster than when it was timed at my buddies shop, by the professional mechanic. I bent twelve intake valves first time so I was gunshy the second time, third time I decided I needed to get the dam thing right...Yes, I have had the head off three times in less than two months...

The only variable was the TDC Flywheel pin was not used the first time. I used it when I did it the last time. If the Tech set the timing without the TDC pin in the flywheel your entire timing could be retarded or advanced causing a large loss of power, as in my car. When I first got it running it felt fast but it was not what I expected after all the crap I did to my car. The second time, when I did it..HOLY SHIT!! I about crapped it was so much faster. Probably at least 20hp difference. you may want to inquire about the TDC flywheel pin or have someone check it..

It fixed my car...

[M3325]

Did you say in ur first post u went from 17 to 18" wheels?

[funkmasta]

A couple things to consider is this:
When they rebuilt your motor did they fill the indents in the pistons?
How was the weather?
People say that tire size doesnt affect dyno results, but I have a hard time believing that (although I dont have much actual dyno experience). Put your 17s back on.
Post your dyno results. Lots of people will be able to decipher your AFR graph.
How did your exhaust valve look after the $$ shift?

[adsingl]

A few things to summarize much of what's been posted:
-if you can't tell the difference, I'd definitely consider going back to original dyno and operator if possible, and I'd get the wheels back if possible, although I don't believe this could affect HP - torque, or how it gets delivered, likely so.
- if you really lost 20 hp, first of all, where, all thru midrange, top end only? - post dyno.
- maybe just as simply, see if you can get cam timing checked on a machine (I'm not certain this is done, but certainly the sensors are there on the intake cam that gets varied by vanos). If what I read on vanos is correct, midrange loss could be affected if they didn't get the vanos onto the very first/possible gear tooth (you have to turn the exhaust sprocket partially tighened to get the helical gear to engage). And certainly if they didn't get the cams right before vanos went on that will affect all rpms. Per procedure they should have rotated the engine two crank rotations and rechecked timing, hopefully with a pin in flywheel, but I beleive you'd see the cams off visually if one missed a whole sprocket tooth. Either way, not that bad a job to recheck.
- temp/humidity can make real difference in runs as mentioned
-----------
Some basics not mentioned so far:
9 months passed, don't know about miles, but what's your air filter look like?
fuel filter good? change oil weights since the first run? any roughness at idle or anywhere else that could indicate manifold/airflow restriction or leak? New plugs go in during head rebuild, if not what do they look like?

Let us know as you learn and good luck!
ADS

[funkmasta]

ADS put another thought in my head... maybe your Vanos is bad or was reinstalled incorrectly? Where was the power lost? good question.

[Blackspeed]

Sorry to hear that you are still having problems. It felt strong to me but I am used driving at a mile high. How many miles do you have on the new Valve system? Did you break it in properly?

When we rode you didn't mention that you had added the wheels during the head rebuild, that would definitely change your dyno. Adding a larger heavier wheel adds rotational mass to the wheel taking away horse power and torque. 20hp? Very well possible.

I just hope my car feels as strong when I get it down here.

Good Luck

[tdwyatt]

...Some basics not mentioned so far:
9 months passed, don't know about miles, but what's your air filter look like?
fuel filter good? change oil weights since the first run? any roughness at idle or anywhere else that could indicate manifold/airflow restriction or leak? New plugs go in during head rebuild, if not what do they look like?

and how many miles pon those O2 sensors? 9 months can be the difference between ok and submarginal..

[bmattick]

Again, what makes you think it's the car and not the dyno?

If you read my original post, you'll see that a number of folks in my area have dynoed their cars on the DSR and Edge dynos with minimal differnce. I'd be fine with 5-10 HP difference, but 20 is just too much to be only the dynos, based on experience of others.

[bmattick]

how many times did you get 245 dyno'd???

what other mods do you have?

3 times. The only mods on the car of the HP making (losing) variety that I have is the full TMS OBD2 cam kit. You can see what that includes in my sig.

[bmattick]

Did you say in ur first post u went from 17 to 18" wheels?

Yes, but the dyno tach pickup should eliminate that, right?

[bmattick]

A few things to summarize much of what's been posted:
-if you can't tell the difference, I'd definitely consider going back to original dyno and operator if possible, and I'd get the wheels back if possible, although I don't believe this could affect HP - torque, or how it gets delivered, likely so.
- if you really lost 20 hp, first of all, where, all thru midrange, top end only? - post dyno.
- maybe just as simply, see if you can get cam timing checked on a machine (I'm not certain this is done, but certainly the sensors are there on the intake cam that gets varied by vanos). If what I read on vanos is correct, midrange loss could be affected if they didn't get the vanos onto the very first/possible gear tooth (you have to turn the exhaust sprocket partially tighened to get the helical gear to engage). And certainly if they didn't get the cams right before vanos went on that will affect all rpms. Per procedure they should have rotated the engine two crank rotations and rechecked timing, hopefully with a pin in flywheel, but I beleive you'd see the cams off visually if one missed a whole sprocket tooth. Either way, not that bad a job to recheck.
- temp/humidity can make real difference in runs as mentioned
-----------
Some basics not mentioned so far:
9 months passed, don't know about miles, but what's your air filter look like?
fuel filter good? change oil weights since the first run? any roughness at idle or anywhere else that could indicate manifold/airflow restriction or leak? New plugs go in during head rebuild, if not what do they look like?

Let us know as you learn and good luck!
ADS

Great advice, thanks!
- The air filter was recently cleaned, and new redline oil went in the engine the morning of the dyno. Same weight oil.
- I was without the car for 6 weeks during the rebuild, so the butt dyno was negatively calibrated down by the wife's VR6 in the interim

I will post dyno results sometime tomorrow after I receive an electronic copy of the latest. If I recall correctly, the torque curve is very inconsistent on this recent run.

I will also follow up with the shop that did the rebuild on the timing and install points that you and others raised.

Thanks to everyone for posting advice, I'm in a bit over my head and this really helps!

BTW, one very scary thought I had- what if they put stock cams back in by mistake?! Now that would be easy to prove...

[bmattick]

Here is the good dyno, with baseline superimposed. I'll post the latest one tomorrow.

BTW, I'm a liar, it was 242.59 RWHP last time, not 245...

[Mad Dog 20/20]

Big/heavy wheels with tall tires can make a difference. But considering you have RCJ's (nice!), I seriously doubt its the wheels, as they are much lighter than stock. I assume you are running 255/35/18's in the rear? Not a whole helluva lot taller than 245/40/17's, either. 245/35/18's are the same height as 245/40/17's. So I'd say something is up w/ the motor . . .

Mmaigret,
I have no clue what the timing specs are for the cams in my motor. Sorry.

[bmattick]

Yeah, the RCJs are sweet. I had the staggered LTW 17s, which are strong and pretty light. The RCJs are much lighter, and in the size I got (18") I can run a 355MM BBK without spacers.

I am running a 255/35/18 in back, as opposed to 245/40/17s in the initial run.

[Blackspeed]

Yeah, the RCJs are sweet. I had the staggered LTW 17s, which are strong and pretty light. The RCJs are much lighter, and in the size I got (18") I can run a 355MM BBK without spacers.

I am running a 255/35/18 in back, as opposed to 245/40/17s in the initial run.
Weight both sets of wheels and tires and calculate the diference in rotational mass. Also Sports Car Revolution (Speed TV) lost horse power on their RSX after adding a BBK and larger wheel package even thou the new pack was lighter due to add in additional mass (not weight) from the center of the wheel.

What tire brands, size and type are you running? I thought I saw S03's on your car and they are HEAVY!

[vjlax18]

Mmaigret,
I have no clue what the timing specs are for the cams in my motor. Sorry.

I'll see if I can find out as mine go in in a couple of weeks. (not Schricks though, but should be the same idea)

[RRSperry]

I don't think there is timing associated with the cams per se, I think it is the combination of the locking devices, (flywheel and cams) that determines everything.

[Mad Dog 20/20]

I don't think there is timing associated with the cams per se, I think it is the combination of the locking devices, (flywheel and cams) that determines everything.

The flywheel i had in the car at the time lacked a dowel pin hole. So I know that using it was not an option for my tech . . .

[Erik@EDGE]

I may have mentioned this when you were at the shop, but here are some reasons why I think you may be having problems.

The Shricks are Billet cams, i.e. not reground from BMW cams. Thus, while close, they don't time perfectly using the little slots as the BMW cams will. To get them right, they need to be set with a dial indicator. There is an easy 20hp in mis-timed cams. I would suggest having someone check them with a dial indicator and re-time them.

[jterp]

Did you remove any stickers in between the dyno runs?

Just a thought.....








:D :D

[bmattick]

Okay, it took a while but here are the before/after dyno runs. Notice how jaggy the power delivery is in the new run. Anyone have any thoughts as to what could be causing this jagginess?

And as a matter of fact, I did remove a magnet from the car after my latest track day... :confused

[bmattick]

I may have mentioned this when you were at the shop, but here are some reasons why I think you may be having problems.

The Shricks are Billet cams, i.e. not reground from BMW cams. Thus, while close, they don't time perfectly using the little slots as the BMW cams will. To get them right, they need to be set with a dial indicator. There is an easy 20hp in mis-timed cams. I would suggest having someone check them with a dial indicator and re-time them.

Thanks Erik. If that's the case, then I'm not sure why the install manual that came with the cams is a factory BMW document. I called TMS and they said that the factory document theu inlclude and the factory procedure it outlines are all that is needed. Can you clarify?

[Erik@EDGE]

Well, in theory, that is all thats needed. Slap them in per the manual. But MANY people, including MRob and my buddy Navid have set them in per that spec and not dialed them in with an indicator and seen the same kinds of results. Navid slapped his top end on my short block, with shricks and everything, but didn't use a dial indicator to set them. Made 228HP. I was making 227 with stock cams and a tired head. he was down about 25hp from his previous engine, but those cams were set correctly. So basically it will run, and run well, but it isnt optimized.

[Erik@EDGE]

The jaggy part seems to indicate maybe bad plugs or maybe a bad coil. Looks like spark scatter. Just a guess though.

[paul e]

I was going to ask you if there were a large temperature differential between the two runs... But when I saw the actual runs, those are differences that temp difs wouldnt begin to account for. Looking at the size, and shape of the differences, I think its most probably related to the cam RE-installation, and not much else. Its not the wheels or tires, its Not the weather, and its most probably NOT the dyno. Something was not timed correctly, most likely.

[bmattick]

Does anyone have any advice for how I can take this up with the shop that installed the cams/re-built the head? Short of shoiwing them a document that says do things a certain way that they didn't follow, I'm at a loss.

[bmattick]

Can anyone shed some light in the differences here? The jaggy curve from the lates dyno pull must mean something.

[NickG]

My first thought was that the cams are improperly timed. But after seeing the graphs, it looks like maybe it's a spark issue. How old are the plugs? Have they been properly gapped?