Considering a cam regrind? Dyno graphs say no?

[ForcedFirebird]

Read a post earlier where someone mentioned regrinds and it reminded me I have three similar files with only cams being the major difference.

The "stock" graph is an s52 long block dropped straight into an obd1 e36m3 race car using obd1 ehxuat manifolds, so all three have no PS, no AC and free flowing exhausts, m50 manifolds. The two cammed cars have headers and free flowing exhaust. One has Riot regrinds, one has Sunbelt and 10:1 forged pistons. The 2 cars were put together by owners, just came for a dyno tune.

Since the owner installed the cams, I am sure there were no lash caps to make up for the cam base circle. Since the 24v don't use rockers, the lash has to be corrected or it'd be like an m20 with loose rocker eccentrics (ie: you actually loose some lift with excessive lash).

As you can see by the similar curves, the cams act similar, just down on power.

[Rugbyfan]

Interesting. Any more details on this? Did all 3 motors have similar miles? Who did the cam installs? Did you do the tuning for all 3?

[Rugbyfan]

My butt dyno may be broken but I felt like I gained a ton with RR cams/TB/TRM tune. I need to dyno.

[ForcedFirebird]

Your butt dyno is broken. Proof is in the pudding. I was clear when posting "owner built". Not sure how clear I can be, whp is whp. I'm a scientist that proves theories. Not sure I can be "less" transparent with data. I'm not a schmuck off the road, dude.

[pazi88]

Since the owner installed the cams, I am sure there were no lash caps to make up for the cam base circle. Since the 24v don't use rockers, the lash has to be corrected or it'd be like an m20 with loose rocker eccentrics (ie: you actually loose some lift with excessive lash).

The hydraulic lifters make up the difference in base circle (up to certain point). If that would not happen, you would horrible lifter noise all the time.


Because those graphs are not from same car, there could be fault in the engine which causes it to be down on power. The cams clearly work because the power curve doesn't drop after 6k. Worn maf for example causes power loss and does not cause fault code untill it's totally broken. Faulty or not correctly installed knock sensors can cause the ecu to pull timing etc.

[digger]

probably a lot going on besides just the cam, i.e many unknown variables. this is why i started measuring cams as the aftermarket world is full of smoke and mirrors BS. if you know what the lobe looks like then you have half a chance choosing a part that's going to perform better

[Rugbyfan]

Your butt dyno is broken. Proof is in the pudding. I was clear when posting "owner built". Not sure how clear I can be, whp is whp. I'm a scientist that proves theories. Not sure I can be "less" transparent with data. I'm not a schmuck off the road, dude.

Pump the brakes, I just wanted more details (mileage, compression etc)to compare apples to apples.

[ForcedFirebird]

Pump the brakes.

:p Just ribbing.

The engines were healthy. It's not normal for me to charge a customer dyno rental and tuning time if the car is not checked out first. Before tuning anything they are required to come in and it looked over. Learnt many years ago that paying dyno rental while wrenching on it, is far more expensive than the base shop expenses.

The customer was actually referred to me by Markert, shortly after he installed the same cams in his drift car, and his car also lost power, so it's been duplicated as far as I'm concerned.

The biggest point is, the cams did not make more than stock, even with a custom dyno tune. When you put enough cars on the rollers, you start to see trends.

The hydraulic lifters make up the difference in base circle (up to certain point). If that would not happen, you would horrible lifter noise all the time.

Maybe a few thousandths, but not on a regrind. Otherwise, it wouldn't be common to include push rods with cams on the domestic pedestal-style rockers stuff we have been selling for years. Hydraulic buckets are only going to make up for so much, and when you drop the preload on them, they most certainly do loose lift. In a Chevy, we use .065" as a target for lifter spring load.

Will it work if you throw a regrind in an lsx without changing push rods, sure, but is it optimal at the end of the day?

probably a lot going on besides just the cam, i.e many unknown variables. this is why i started measuring cams as the aftermarket world is full of smoke and mirrors BS. if you know what the lobe looks like then you have half a chance choosing a part that's going to perform better

It's annoying, and have no idea why BMW cams sellers are like that. Been working with Comp Cams for years and they provide up to 20 points of data on their lobes, and even have a lobe library that work in Dynomation.

[Rugbyfan]

Would you be willing to do a same day install with before/after dyno? That seems to be the most scientific vs comparing dynos between cars. I’m not emotional one way or another, just an observant consumer.

P.s. did that hub make it in the mail?

[ForcedFirebird]

Would you be willing to do a same day install with before/after dyno? That seems to be the most scientific vs comparing dynos between cars. I’m not emotional one way or another, just an observant consumer.

P.s. did that hub make it in the mail?

Yes, ideally, before/after would be definitive.

...and holy crap, apologies, still been tripping over the stupid trailing arms purposely left at the shop door. My bad.

[pazi88]

Maybe a few thousandths, but not on a regrind. Otherwise, it wouldn't be common to include push rods with cams on the domestic pedestal-style rockers stuff we have been selling for years. Hydraulic buckets are only going to make up for so much, and when you drop the preload on them, they most certainly do loose lift. In a Chevy, we use .065" as a target for lifter spring load.

Will it work if you throw a regrind in an lsx without changing push rods, sure, but is it optimal at the end of the day?

I have zero idea how those pushrod engines are built. But the stock lifters in m5x can handle more than 2mm smaller center circle no problem (1mm more lift than stock). The lifter works as it should if the oil feed hole still lines up when there is zero lift on valve. The regrind cams are quite common practise and work great if done properly. If not the engine will run horribly. There is quite much lifter noise or if the center circle is too small, the valves won't seal and the engile will not even idle. I have seen this kind of cams and those had about 3mm smaller center circlem probaply made to be used with solid lifters

From the dyno sheet, i would still say that cams work fine. There is some othet fault in the engine.

[Northern]

These Riot regrind findings aren't so different from what others have said. I think it was Dave who posted similar graphs a while back, and there was at least one more person who claimed to not get anything out of them.

[st.petebiodiesel]

This thread disproves your theory.
Guy made 215whp on his bolt on S52.
Installed some regrinds, and made 232whp.

https://www.bimmerforums.com/forum/showthread.php?1920791-Riot-Racing-developed-regrind-camshafts-review

Sent from my SM-G960U using Tapatalk

[ForcedFirebird]

I have zero idea how those pushrod engines are built. But the stock lifters in m5x can handle more than 2mm smaller center circle no problem (1mm more lift than stock). The lifter works as it should if the oil feed hole still lines up when there is zero lift on valve. The regrind cams are quite common practise and work great if done properly. If not the engine will run horribly. There is quite much lifter noise or if the center circle is too small, the valves won't seal and the engile will not even idle. I have seen this kind of cams and those had about 3mm smaller center circlem probaply made to be used with solid lifters

From the dyno sheet, i would still say that cams work fine. There is some othet fault in the engine.

Lifter are lifters. They work the same in a pushrod engine as a OHC regarding the hydraulics, just there's a pushrod in between, and "upside down". Because they are hydraulic, they won't make noise unless you go below 0 prelaod.

1mm is a mile when talking lifter preload.

Again, Markert did the same and got the same results. Otherwise, I would have dismissed this notion. His car lost power after a cam change. He installed them AFTER this car was dyno'd and it clicked when we were chatting about this client's car.

You would have to make the base circle larger to hang the valves open. Making the base smaller increases lift at full open, not at valve closed.


...and the engine wouldn't run improper or poor, it will just be down on power as if the cam was smaller.

Installing a hydraulic camshaft when there is no
provision for valve adjustment (such as adjustable
rockers or push rods) requires special attention
to several measurements and clearances to avoid
noisy lifters or breakage.
There must be a clearance of .020” to .050”
between the retaining snap ring and the top of the
lifter push rod seat when hydraulic lifter is on the
cam base circle. If the clearance is not correct,
steps should be taken to remedy the situation.
Incorrect clearance in the hydraulic lifter can
occur if the following elements deviate from stock
measures. Look for changes in:
1. Cam base circle diameter (smaller or larger).
2. Lifter height due to different manufacturer.
3. Push rod length.
4. Head gasket thickness.
5. Heads due to resurfacing, milling or several
valve jobs.
6. Valve stem due to facing of end.
REMEDIES
1. Install different length push rods that allow
proper clearance.
2. Install adjustable push rods.
3. Install adjustable rocker arms.

Animation of the inside of a hydraulic lifter:

https://www.youtube.com/watch?v=lorANZ1Tptw

The hydraulic is only to keep 0 lash, not to actually open the valve.

The pressure from the oil is only just enough to remove whatever clearance there is in
the valve train, but not enough to actually open the valve itself

[ForcedFirebird]

This thread disproves your theory.
Guy made 215whp on his bolt on S52.
Installed some regrinds, and made 232whp.

https://www.bimmerforums.com/forum/showthread.php?1920791-Riot-Racing-developed-regrind-camshafts-review

Sent from my SM-G960U using Tapatalk

I was thinking the same thing as this guy...

I'm lost... 232 with cams is good now?