RPM range
 

I'm installing a Crane 104227 210/224 cam with 1.6RR and beehive 918 springs next week. The recommended rpm range for the cam with 1.5 RR's is 2,000-6,000. Can I expect higher rpms with the 1.6RR's and beehive springs?

Re: RPM range
 

Not with that cam, you need more duration to run more rpm. I like this cam better: 224/230 duration, .536"/.544", 112lsa. It should work fine with your car since you have a decent stall in the car. If you want something with a relatively mild lope go with this one: 221/227 duration, .542"/.560", 114lsa.

I think you'd be happier with either of these two cams.

Justin

Re: RPM range
 

I'm interested to know where people are shifting at with this cam.

Re: RPM range
 

Even thought the "power band" is stated that it's good to 6000 rpm, that cam will like to be shifted higher than that, especially with the 1.6 RR's.

My bet is that the optimal shift point is higher than you are going to want to rev your engine, like 6500 rpm+. Now that's with an M6, I'm not sure about the A4, I would have to do the plots to find the optimum shift point on a A4.

Just for reference, my optimal shift point is 6000-6100 rpm and all I have are CAI, headers, catback and 1.6 RR's. Put a cam in there that breathes a lot better up top and it will shift your optimal shift point at least a few hundred rpms higher than what I'm shifting at.

By the way, I like that cam a lot. Guys have some excellent times with that cam, even relative to "bigger" cams.

Dan

Re: RPM range
 

What method did you use for this calculation?

Rich

Re: RPM range
 

Rich, I made an Excel spreadsheet that I enter in the dyno TQ numbers. Knowing the dyno curve and tranny gear ratios, I can calculate the crossover points where you need to shift into the next gear.

For an auto:
Excel Spread sheet for an A4 auto

Go to the first sheet on that file, labelled TQ vs Speed Data. Enter in your torque numbers into column H and then you can see where you need to shift at, in the sheet labelled shift point chart.

:edit: File has been updated and complete

Of coarse, you want to stay in your current gear as long as possible, until the TQ in the next gear is higher, at the same speed, as your current gear. For the auto, it looks like the gear ratios are pretty spread apart, so you have to rev VERY high before it makes sense to shift into the next gear based on TQ, even stock. You most likely will shift based on your engine and tranny safety. For an M6, the gears are much closer, and shifting to the next gear comes sooner in RPM than with the A4.

Dan

Re: RPM range
 

Sounds like you did it the right way.

Rich

Re: RPM range
 

I wish I had ms excel. I just look at the dyno sheet and shift 100 rpm after the hp starts to decline. Is that wrong Rich?

I have a comp cam XE 218/230 @.050 .528/.536 lift w/1.6rr's ground straight up on a 114lsa. The car has ported stock heads and the car's power peaks @5800. I still shift at 6500 rpm b/c I run quicker times not having to shift as much.

The crane cam mentioned above is too small imo which doesn't amount to a hill of beans. Acutually b/c you have an auto I think my cam would be perfct for you and you can set up the shift point at 6200 rpm the car will run very good and your engine and tranny will be able to handle the rpm. It might even have more vaccum and idle better than the crane cam.

Justin

Re: RPM range
 

An old rule of thumb is 10% over peak HP RPM. This also depends on gear.Ya may wind up with a differant RPM for each gear,which is not unheard of.

IT'S only a RULE of THUMB

Re: RPM range
 

Looks like I'll need a dyno to set that chart up right for me. Well, it's not like I wasn't going to get one anyways. Thanks.