Oooo what are the specs for those?
As I said earlier its such a shame so much of this engine build will be hidden when its finally up and running but that's not an excuse to leave things plain !! Valve springs were specially ordered from Germany specifically for this engine/cam spec . When we first ran this cam spec with the usual type of spring used they failed on the dyno causing a massive loss of power which had us bamboozled for a while .once sorted we did get 375 BHP at the flywheel with the engine as it was in the opening photo . The springs ,retainers etc are all available from David at DTM Power here in the UK . Image Unavailable, Please Login
Regarding valve springs, I found a similar issue when running P6 cams, the ramp on P6 cams is so radical and quick that it caused irregularities starting at around 6500 on up, the issue only really showed up on the dyno. Funny thing is the P6 cams don't have a huge amount of lift really, just tons of duration and they throw the valve open extremely quick. This was with stock springs by the way. Myself and a couple others here are running Cat cams with about 11mm and I came up with a more suitable spring which has about 90lbs seat pressure and 200lbs at full lift. I think with the stock springs that the seat pressure is the primary issue and not so much the spring rate or full lift value which are both pretty good. Can you tell me about your spring specs? You have me curious! PM me if you prefer
Sorry everyone following this thread, but I have been working away with Mercedes on a promotional tour and I am just leaving on another one with AMG tomorrow. Hope this isn't heresy on a Ferrari forum, but it pays the bills? (some of those AMG machines are monsters as well!!). When I get back I promise more detail on parts and updates on Ferrari projects progress. There has been loads! 550 Maranello brake conversion, 308 GTB strip down, GT4 LM car build, 458 suspension mods, F355 twin turbo, 308/328 drop gear ratio change sets, GT4 carbon/kevlar bodywork, electric water pump conversion ... watch this space! Oh yes... and I will weigh the flywheels referred to.
What a great thread! As I currently have the engine out of my GT4 (Ferrarifxr rebuild my gearbox) this has me wondering if this isn't the best time to make some mods. DCNF's are in pieces, getting new sealed bearings. And I've toyed with the notion of just dumping them for a turbo. But not sure that's worth the added expense either. But it would probably give it a significant boost. The mods in this thread though are very intriguing. I just wonder what it would cost to have the heads and valves done at this point. My motor has less than 2000 miles on a $16k rebuild that was done about 2years before I bought the car. So maybe doing more to it would be a bit of a waste. But then again, I did not pay very much for the car and I only - by chance - found out about the re-build a few months after I bought it from the PPO (prior owner was unaware) who had the work done and graciously sent me the receipts. Sooo....??? Hmmmm.... More decisions.
With a naturally aspirated engine, everything has to match another components capabilities. In other words, you can't do just one thing and expect anything other than nominal results. For instance, if you flow the heads a bit better and install slightly higher lift cams you may experience a slight bump (hardly noticeable) in power, but the heads are no longer matched to the stock bottom end capabilities of the engine. If one were to flow the heads, higher lift cams, and bump the compression you would most certainly experience a good bump in power as you have match components well. Just understand these are Ferrari engines so just about everything is a custom job and there are only a few people on the planet who have a good understand of the capabilities of such modifications.
Yes, I am aware of that. Thanks. I am becoming increasingly aware of the potential bottomless pit. One of the points of getting a GT4 in the first place, was to avoid that. The anti-thesis however (or at least one of them), is that it makes it far less expensive (in the end) to step down into it. ...just a wee tad, of course!
The way I see it is if you are already rebuilding the engine, it doesn't entail a huge amount more effort to modify the engine internally a bit to essentially work better, with the exception being a 360 crankshaft which are getting a bit more pricey these days, but the juice is most definitely worth the squeeze
