| Author |
Message |
Rob Schermerhorn (Rexrcr)
Member
Username: Rexrcr
Post Number: 428
Registered: 11-2002
| | Posted on Thursday, March 27, 2003 - 12:20 pm: | |
Non-racer? My personal cars over the years have ran great at 18%. For Ferrari, I'd keep driving until it was more than just a not-great leakdown test. For example, I had a 348 Challenge that we finally rebuilt the heads on because we couldn't get it to idle anymore. That one had four holes at 28% leak, and four about 14 - 18%. Valves and guides, leaked at 0% - 2%, didn't touch the bottom end at all other than inspection.
Keep driving until other symptoms crop up, or you're certain other damage will occur. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 4147
Registered: 12-2000
| | Posted on Thursday, March 27, 2003 - 8:53 am: | |
Rob, at what leak down numbers do you start recommending a rebuild to a track day person only?
Also, will it show one bad cylinder or do they all start going out together? My 328 put up great hp/torque numbers on the dyno, but has one cylinder with a bad intake leak down.
Thanks! |
Rob Schermerhorn (Rexrcr)
Member
Username: Rexrcr
Post Number: 422
Registered: 11-2002
| | Posted on Thursday, March 27, 2003 - 5:57 am: | |
BTW, I'd go two years or more between top end rebuilds, too. Just keep doing leak downs, the wear will show there first.
That's probably 20+ days at the track, 72 hours, maybe 6500 race miles per year. Pretty durable race engine, I'd say. |
Rob Schermerhorn (Rexrcr)
Member
Username: Rexrcr
Post Number: 421
Registered: 11-2002
| | Posted on Thursday, March 27, 2003 - 5:51 am: | |
I put more importance on the leak down percentages. It's all good, Rob!
A totally fresh engine will leak 0% - 2%. This one's still good to go. Sure, it has miles on it, but IMHO, looks good, even at 10%, unless you were a pro racer with a pro budget, it still is just fine.
There are enough variables in compression testing that I would not definitively say 1-4 is fresher than 5-8.
I certainly would like to know the complete service and race history, too. If the owner can provide all that data, that's worth money to him, and peace of mind to you. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 4140
Registered: 12-2000
| | Posted on Wednesday, March 26, 2003 - 4:06 pm: | |
I think they will run for a long time, but with how much Challenge racers were already spending, most rebuild every 2 years just to get every little bit of HP. To a track event person it's not a big deal, there is a 355 C racer in the SCCA that rebuilt his engine at a dealer for $25k and improved his TWS times about a second per lap. That's a bunch of time in club racing, but not very noticeable unless you're looking at the stop watch. |
DWE (Dwe)
New member
Username: Dwe
Post Number: 3
Registered: 3-2003
| | Posted on Wednesday, March 26, 2003 - 4:03 pm: | |
Have most of the 355 challenge cars had engine rebuilds? What is the normal mileage between rebuilds?
And also, what does a top end / top and bottom end rebuild usually run cost wise?
I would expect pretty good life out of the motor, since it is essentially unchanged from stock. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 4139
Registered: 12-2000
| | Posted on Wednesday, March 26, 2003 - 4:00 pm: | |
This was done by the shop with the car, I wasn't there. |
Dan (Bfs426)
New member
Username: Bfs426
Post Number: 3
Registered: 3-2003
| | Posted on Wednesday, March 26, 2003 - 3:50 pm: | |
Did you have a battery charger hooked up when you did the compression test? It looks like you did one cylinder bank and then did the other. It looks like the battery started to die. Did you also do a cylinder leak down? Is that what the "4 warm," "6 warm" means. |
Bob Campen (Bob308gts)
Member
Username: Bob308gts
Post Number: 473
Registered: 9-2001
| | Posted on Wednesday, March 26, 2003 - 3:36 pm: | |
Take a look at the rebuild tickets, the 1-4 head may have been surfaced and not the 5-8. If that was done to cut expenses, what else was shortchanged. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 4137
Registered: 12-2000
| | Posted on Wednesday, March 26, 2003 - 3:26 pm: | |
The engine was rebuilt about two years ago and hasn't had that many miles since. |
Martin - Cavallino Motors (Miami348ts)
Advanced Member
Username: Miami348ts
Post Number: 4105
Registered: 5-2001
| | Posted on Wednesday, March 26, 2003 - 3:22 pm: | |
...and 5-8 is kind of weak.
How does that effect the smoothness of the engine if one bank is up to 35 different???
|
Bob Campen (Bob308gts)
Member
Username: Bob308gts
Post Number: 472
Registered: 9-2001
| | Posted on Wednesday, March 26, 2003 - 3:16 pm: | |
If the cylinder numbering is the same as a 308, it would appear the 1-4 head has had recent work. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 4136
Registered: 12-2000
| | Posted on Wednesday, March 26, 2003 - 2:56 pm: | |
What do you think?
Cylinder #: Compression: Leak Down
1 210 Cold
205 Warm 4 Warm
2 210 Cold
210 Warm 4 Warm
3 215 Cold
210 Warm 4 Warm
4 205 Cold
205 Warm 6 Warm
5 195 Cold
175 Warm 4 Warm
6 195 Cold
180 Warm 6 Warm
7 185 Cold
175 Warm 6 Warm
8 180 Cold
175 Warm 6 Warm
|