John B Posted April 2 Share Posted April 2 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 😛 Quote Link to comment Share on other sites More sharing options...
JohnCh Posted April 2 Share Posted April 2 Wow, that should be fun! What is the suggested redline with that crank? Also, what drove the reconfiguration of the cam drive? I know the stock hydraulic chain tensioner raises concerns in some circles, but I've never heard of anyone moving to belts before. Thanks, John Quote Link to comment Share on other sites More sharing options...
yellowss7 Posted April 2 Share Posted April 2 (edited) Sounds like a beast John. When Croc finishes CATkong that will make three of us in the 300+ club. Let’s go guys. It’s been lonely up here for so long. Tom. Edited April 2 by yellowss7 Quote Link to comment Share on other sites More sharing options...
Pokey Posted April 2 Share Posted April 2 You guys are killing me. My bone stock Seven hasn’t reached its first birthday yet and not seen but a few road miles but now it needs a Cosworth. I need help I think. Quote Link to comment Share on other sites More sharing options...
Vovchandr Posted April 2 Share Posted April 2 Even if I make the supercharger fit I don't expect 300hp out of the Zetec. Wow. Quote Link to comment Share on other sites More sharing options...
yellowss7 Posted April 2 Share Posted April 2 3 hours ago, Pokey said: You guys are killing me. My bone stock Seven hasn’t reached its first birthday yet and not seen but a few road miles but now it needs a Cosworth. I need help I think. The 420 spec is a great package. Plenty of power without the drama. Ours are just a little faster on the straights. No skill required to do that, only deep pockets. Quote Link to comment Share on other sites More sharing options...
Croc Posted April 2 Share Posted April 2 9 hours ago, John B said: 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 Who? I? I thought it was your son finding 10,000rpm? Fathers' never make mistakes remember! Good to see you are on a road back to having fun in your Caterham again! Quote Link to comment Share on other sites More sharing options...
John B Posted April 3 Author Share Posted April 3 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. Quote Link to comment Share on other sites More sharing options...
John B Posted April 9 Author Share Posted April 9 Final pull: 325 hp @ 8.100 244 tq @ 5,700 Quote Link to comment Share on other sites More sharing options...
Croc Posted April 9 Share Posted April 9 Impressive result. No reason to ever go above 7500rpm based on that plot. Impressively flat power delivery curve across the rev range. interesting how the torque curve tapers starting at 6000. Here's hoping third time is the charm for you. Quote Link to comment Share on other sites More sharing options...
John B Posted April 9 Author Share Posted April 9 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. Quote Link to comment Share on other sites More sharing options...
Pokey Posted April 9 Share Posted April 9 @John B, sorry if you already mentioned, but what fuel was used to get those numbers? Quote Link to comment Share on other sites More sharing options...
John B Posted April 9 Author Share Posted April 9 It was dyno’ed on 93 octane pump gas Quote Link to comment Share on other sites More sharing options...
Pokey Posted April 10 Share Posted April 10 26 minutes ago, John B said: It was dyno’ed on 93 octane pump gas Very nice! Sorry to pepper with questions, but your answer does beg the question as to the compression ratio? Just wondering if a little racier fuel wouldn't bring out a fair bit more power (not that it is needed, of course). Quote Link to comment Share on other sites More sharing options...
Croc Posted April 10 Share Posted April 10 Even more impressive results on 93 octane. Calling @SK400 to this thread. I'd upgrade your new engine if I were you. Quote Link to comment Share on other sites More sharing options...
Kitcat Posted April 10 Share Posted April 10 The turbo'd Zetec on BAT makes 261 hp and 223 torque. So not close to these very impressive numbers (esp on 93 octane!). What transmission are you using and is it stout enough for all of this power? How often does this engine need to be refreshed by the builder? Quote Link to comment Share on other sites More sharing options...
John B Posted April 10 Author Share Posted April 10 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... Quote Link to comment Share on other sites More sharing options...
Croc Posted April 10 Share Posted April 10 John - your car has a Ford T-9 box. I remember it from the previous owner to you. Not sure a T-9 will last long with that hp - watch the synchros as they will go first. Quote Link to comment Share on other sites More sharing options...
John B Posted April 10 Author Share Posted April 10 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? Quote Link to comment Share on other sites More sharing options...
wemtd Posted April 10 Share Posted April 10 I know quantum mechanics in oxford ct has been the go to shop for our gearbox repairs.. do you have other shops on retainer? Quote Link to comment Share on other sites More sharing options...
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