John B

Thanks Croc. it held up with the 2272 hp MZR. i’ll be careful with it. but... Just in case, what’s a good Plan B?

I think the C.R. is 12:1 but am re-checking with Hasselgren. The 2.3 Cosworth Duratecs used in the Swift 016 Formula Atlantic racecars spend most of their life at 8,900 rpm and get get rebuilt at 15 hours (1,500 miles). This engine will probably have an average rpm of 3,500 throughout it's life with brief spurts up to 8,000 on the street. But it will get a few hours of 7,000-8,000 at track days. I'll log track time and shoot for a rebuild after 20 track hours (about 10 track days). I'm not sure what the trans is, but I know it's not a Sadev. It's a 5-speed of some type. The car is a 2003 SV that originally had a 2.3 Duratec. The Diff could be a weak spot as well...

It was dyno’ed on 93 octane pump gas

It looks to me like it "wants" to live between 7,500 and 8,500, where the power stays about flat at max. But... given that I'd rather not turn this one into a coffee table, I'll keep it below 8,000.

Final pull: 325 hp @ 8.100 244 tq @ 5,700

Correct Croc, it was actually my son that made it go boom. Both times actually... This one will rev to 8,500, but I’ll mostly keep it below 8.

I’m in!

Well it’s been about a year and a half since I blew a hole in the block of the 2.5L MZR engine in my SV at a NJMP track day late in the summer of 2019. Covid induced delays at my engine builder Hasselgren Engineering slowed things down quite a bit. I’ve suffered a fairly severe case of Caterham withdrawal as a result. My wife and I are on a trip out to Santa Clara, CA to visit our son and we drove around the Bay area doing some hikes and stopped for lunch in Berkeley, where Hasselgren’s shop happens to be. Paul Hasselgren has been building the race engines in the Formula Atlantics my son and I have been racing for quite a few years so I naturally wanted to pop in and pay a visit. It was pretty much pure coincidence that this happened to be the day my engine was on the dyno. Paul has done quite a bit of development on it and we went back from the 2.5L stroker crank that failed in favor of a Billet and balanced 2.3L crank. The engine is basically a short stroke 2.5 MZR with a bigger bore and a balanced billet crank from a Cosworth Duratec The whole front end of the engine has been redesigned to run a belt drive for the cams. I was hoping to get a little more power than my previous 2.5 MZR with this higher revving configuration, but I was quite surprised by the result. 312 hp at 7,500 and still climbing. 241 peak torque @ 5,900. Paul says he’s not done yet. He thinks he can get 320 out of it, which will be limited by the barrel throttle dimensions. A redesigned barrel throttle can unlock even more. Paul cautioned this one will hit hard. Good! I can’t wait 😛

For me personally a lot depends on the intended use. Generally, these are my criteria for cycling tires. Daily Driver used for routine local errands: Black Round Tread remains Hold air High performance street car: four above plus the 6-year life. Race car: 6 heat cycles.

Congratulations Craig! Well deserved

Croc - Make sure you use a billet or forged crank in the 2.5L Duratec

I just got up to speed. Your new car sounds awesome Croc! One thing, and I'm speaking from experience here, make sure you use a forged or billet crank! You'll have to have it custom made. That's basically the same engine I had in my Cat when we blew it up last year but engine builder figured a cast 2.5L crank from a Ford Ranger pickup would be ok because it's a street car. - NOT! How was the event? I need posts and pics

Oh Ohh! What did Croc get? I think we're squeezing all we can out of this NA Cosworth Duratec

I still don't have my engine back from my builder in CA :toetap05: So I'm not going to make this one. Have fun and stay safe! Best to all, John

It's touch and go if my engine will be ready, but I optimistically signed up :driving:

The thought has crossed my mind...

Wish I was there. My engine's still in CA.

Hi Croc - I'm not really sure what the HP will be, we're breaking new ground here. For a guess, it's almost the same displacement as the 2.5 which made 200 lb-ft of torque at 7,200 and 274 hp. If we can make maybe 180 lb-ft but about 1,000 rpm higher that could get us over 280 HP. We'll see soon. I'll keep you posted.

I kind of forgot the Cosworth 2.3 Duratec revved to 8,800. That's Formula 1 and Winston Cup piston speeds. (27.5 meters per second avg, 43.3 max). The short stroke engine equivalent would be close to 9,100 but I don't think I'll push it that hard. We'll see what the torque and HP curves look like.

Croc, Just go faster and catch 6th going under the bridge

Kitcat: Probably 8,800-8,900 rpm to keep piston speeds the same as the 2.3 Cosworth Duratec.

I'm in for October! I'm still working on the new engine as our crank failed spectacularly last year. Rather than the high torque, lower rpm stroker engine we had last year we're going oversquare and high rpm this time, which is more up my alley. It'll be a 2.42L Cosworth/Duratec built by Hasselgren but we're using a 2.5L block further bored and a short stroke billet crank (shorter than the 2.3 Cosworth) so the engine should be a screamer. I'm looking forward to dyno results and testing.

I also could not see below #81, but the list better include a Lamborghini Miura, Mclaren F1, and an Alfa T-33 Stradale...

I'm in!! My engine is out in California being rebuilt at the moment. It turns out it did not have a forged crank. Now it's getting a billet crank and we'll try again! We'll get this thing sorted... Best, John B

RIP Jesse, Never lift