TD in DC

I have the impression that the writers of racing rules are worse than attorneys.

I never feel certain that I know the answer to whether I can do something or not when I am finished reading the rules. Hopefully my interpretative skills will improve with practice.

I am getting ready to swap motors out of the 944. On Clark's garage, they say to check the motor mounts. Would it be a good idea to replace the motor mounts since I will have the motor out anyway? If so, should I use oem rubber mounts, or move to solid mounts. Would that bump me up a class? What are the advantages/disadvantages to oem vs. solid motor mounts on a track car?

M758

Solid motor mounts means less flex so may be 1 more hp to the ground?

Their down side is extra noize and vibration.

Not sure about their legality. PCA Stock probably no, SCCA IT? maybe Geo?. For 944 cup the car must be PCA or SCCA legal with their allowances. I know they are not legel for 944 spec, but then again that is not a concern given your region.

I'd bet you could run OE mounts and be just fine.

Carrera51

TD: Solid motor mounts are legal for "stock" PCA cars. Like Joe said, more noise and vibration.

Disclaimer: I do not have solid mounts in my 911 racecar. My stock ones have yet to fail so why bother.

Professor Helmüt Tester

Solid motor mounts not legal in SCCA ITS.

(WARNING ! OPINION FOLLOWS !!!) I put them in the same category as 'short-shifters' - their only benefit is to the balance sheet of somebody manufacturing or selling them.

I can't, for the life of me, get my head around 'solid motor mounts' in a production-based chassis. What are the benefits - 'real-world' benefits ? If you can't measure it on a dyno, then (to me) it doesn't exist. Yes...that puts me in the 'cranky old-technology racer curmudgeon', but there are so many more cost-efficient ways to spend money on useless race car doo-dads. Why spend big money to screw up a car, when you can do so effectively for mere pennies ?

Adam Richman

But you could run one engine stayrod per IT rules should you be so inclined (seems like it could get you in the same neighborhood ??).

One other opinion on solid engine mounts and this is only opinion; if perchance you bottom out the oil pan, I'd fear what collateral damage could occur if there was no give between the engine and chassis.

BTW, straddle the curbing entering the crossover at VIR-N and you will bottom out the oil pan. I cannot imagine how bad this could have been (http://www.eurowerks.us/videos/NasaVIR-N_offTrack.wmv) if there were solid motor mounts in the car (as it were, just a broken external fin off the bottom of the oil pan).

Professor Helmüt Tester

Think of the dynamics involved in whacking your oilpan hard, then go feel the compliance of a typical motor mount. IMO, if you hit it hard enough to break it, it'll break, regardless of whether it's a solid or rubber motor mount.

Not to side-track the thread...but this is why I always opt for a steel oil pan vs. an alloy/aluminum one. I've dinged my share of oil pans, in all sorts of race car chassis', but the only ones that cracked or broke were aluminum or alloy. 'Heat transfer' etc. doesn't mean diddly-squat if all the oil is lying on the track and you've got a rod sticking thru the side of the block.

Adam Richman

I would not argue that at all. I could have said it better as improving your margins, not a end all solution. Yes, you hit it hard enough it will break the pan or block even if you hung the motor on springs. I was thinking of the gap there between a hit that will break anything regardless and something where a little give is a good thing.

And to your side-track, I have had very good fortune w/ steel pans as well. And had one with a huge kerplunk that we think improved its baffling

Geo

Herr Professor is of course correct about the IT rules. As for why run them? In my case, I would do it if I could because the longevity of the mounts leaves something to be desired. I'd also run a short shifter if I could simply because I like the feel, not for any competitive advantage.

Bill L Seifert

I bought my 83 944 (Which I still race) in 1989. The mounts were shot, so in early 1990 I changed to turbo mounts. They are still in the car, and in good shape, after 80k street miles street till 1987, and strickly race since then. 10-12 races a year, including one 10 hour enduro, I really can't see the purpose in solid mounts, when I have almost 16 years on turbo mounts, and they cost about $80. apiece. Also, BTW, if I go to VIR I will put the skid pan back on, if I can find it. That brings up a question, Geo, is it legal to run without the skid pan?

Bill Seifert

Geo

Bill, I'd have to consult the ITCS, but my guess would be that it can be removed under the same provisions that allows you to remove fender liners and such. I'm not 100% positive about that though. You really want to run with it though because it will improve cooling efficiency.

M758

Bill that factory undertray will provide zero protection to teh oil pan. It covers from the radiator frame back to the cross member. The pan is behind the crossmember. You could probably fab a skid plate to protect the pan, but I am not sure how the rules would related to that. I may fall foul of general rules or specificly to the ride height as any proper skid plate would be a little lower than crossmember.

As for the OE mounts. Well... for a hard raced 944 you probably should be doing rod bearings at least once before the mounts wear out. Of course if you are doing rod bearings the mounts are an easy change.

TD in DC

That's what led to my question. I have tried to order all the parts I need for my engine swap because I don't have much time if I want to make it to VIR with NNJR. I was trying to decide whether to just go ahead and order motor mounts as preventative maintenance (so that I will have them already when we are doing the swap), and if so, what type to get. The solid mounts are actually cheaper, which is why I asked about them.

M758

I would put the stock ones in.

How many days do you have for the engine swap?


It takes me 4 hrs to pull a motor from my 944 race car. That is is knowing what I need to pull and not having various accessories to get in the way and with father's help. I'd figure at best with two people you are looking at 8 hrs to pull and 10 hrs to replace minumum. This accounts for learning curve on the way out and the way in and minor hiccups (for example it can take 45 min to pull the 4 bolts on the torque tube to bell housing. 3 are pretty easy, but one is hard to get leverage on. It usally take about 2 swivels and 3 extensions of various lenghts all comboed together to be able to get enough leverage to loosen. Have a major issue like a stuck/busted bolt and you can be down for 3 hrs just for that.

maybe it would be better to just drive the 996. Take it easy and feel how different the car feels now than it did before. Plus if you have time off in the winter you can rebuilt the current engine and that maybe better than putting an temporary motor in the car now.

just a thought.

TD in DC

All of my sensible friends are telling me to do exactly that. I have until November 10th to finish the swap.

Why am I so against taking the 996 now? Well, I am worried about my safety. That's right. I think I am driving so much faster now than I was when I started that it is a little frightening to think what could happen if I wadded up a 996 Targa that has stock seats, 3 point belts and no roll bar. Also, I could not use my ISAAC.

I really try to be a safe driver who is in control. Nonetheless, I like pushing the envelope. Although I haven't had the '44 very long, I am driving much more aggressively (and better, I think) in that car, even though it might not be so evident from the outside. I think that if I get back in my 996, even now, I will be hitting some pretty incredible speeds. I was hitting 135 at VIR last April. That is surely fast enough to get into trouble, and I can imagine that I might even be a little faster this time.

I think it would be better for me to struggle to try to get this new motor in and drive a car with (1) a full cage; (2) racing seats with back braces and 6 point harnesses; (3) fire supression; (4) electrical cutoff switches; and (5) ISAAC system.

Also, and I know this is kinda silly on my part, but I view my 944 experience as a form of "HP diet." Just like anybody else, I love HP. But I went cold turkey because I knew I would be better off in the long run. If I start jumping back into the 996 at this point, it might just give me the shakes again

M758

Well funny thing.

I have a low hp 944 race car 134 rwhp and "high" hp 944 Turbo Street car "230 rwhp"

I had been driving the 944 for a few months and took the Turbo to a DE. That was the last DE the high hp turbo car saw for 3 years.

Why? Power was great, but the car sucked in the corners. Too much weight, too much body roll, not enough grip from the tires. I feel handling withdrawl more than feel of the hp crack pipe.

I had friend with a 944 spec car and 400 rwhp 944 turbo street car.

He would race the spec car and on occasion DE the Turbo car. Never liked DE'ing the turbo car cause it had no grip. He said it had too much hp and sold it. No fun any more. He did fine giving up HP, but could not stand the pigish feel of street car even if it had close to 300 MORE HP.

I do understand the safety issue. After one run my friend parked is turbo car. He said he hit about 260 kph indicated (160 mph) down at the end of the front straight then got on the brakes. Said the car did not stop like his spec car and nearly crapped his pants trying to make the turn. I think that was his last time on the track in that car.