Hartech oversized engine testing.

After a few occasions of Baz Hart trying to persuade me into visiting Hartech and test driving some of their development M96/97 oversized engines I finally gave in and with an opportunity of nipping out of work for a few hours today seized the moment. It's not my first visit over there but just as exciting every time. They run an amazing operation in there from when they 1st get the cars up on the ramps to boring out and relining mashed blocks, before assembling everything back together and back on the road for testing. The whole process is just mesmerising to walk through. Anyway, I wasn't there to gawp over the flawless rebuild process, but to take a couple of 996s out for a spin and see what benefit an oversized engine gives. The 2 cars in question were some of Hartechs own development cars, specifically used for testing out new engine development: 1. 996 Gen 1 manual coupe M96 3.4l increased to 3.7l 2. 996 Gen 2 tiptronic cab M96 3.6l increased to 3.9l Took for 3.9l tip out 1st, which was different as I've never driven a 996 tip before. Fortunately Tobias was at hand with the smelling salts between gear changes (ok ok I'm not a tip fan so don't start flaming me :grin: ) but the rest of the time, they were redundant. What did I notice, well there's definitely an increase in clout round the lower part of the rev range around the 3 - 4.5k bracket. Normally these engines don't come into action until high up in the rev range around 4.5k and anything before that seems a bit flat. But this larger engine feels like the power band has dropped 1k or so down to the early 3k mark. Obviously done by increasing the torque on the engine to give it more umph earlier on. I suppose the best way to describe it is similar to a modern day turbo diesel , but without running out of puff after 4k. It's also smoothed out the power curve so the acceleration doesn't seem as flat early doors before the horses bolt. I wouldn't say that there's a huge noticeable difference with the bigger engine, more of a subtle sweetener that fills that void of lameness mid range before the excitement starts. Something that I've heard a few slate the 996 for and also felt myself it's just lacking a little something earlier on. Once back at the ranch it was Baz's turn to take me (as a passenger this time) out in the Gen 1 3.7l. Good call really as the 3.7 hadn't been tested in anger as much and I didn't want to be the culprit of breaking a development engine. So, a nice leisurely drive to warm up round some of the back roads, then on to the A666 (The Devil's Highway :lol: ) over to Darwen and back for a blast. Pretty much the same as the 3.9l. Well, same experience in the rev ranges but with a little less clout than the 3.9l.....although still filling that same void experienced with the 3.4 as well. To conclude, would I get my car over there quick sticks to have these guys work their magic and deliver back to me a Gen 1 3.7l? Well, if money was no object - yes!! Am I going to? Not yet. If my engine needed to go in to these guys for a rebuild through some mechanical wear or failure imminently then I think I can safely say though, it would be coming back to me as a 3.7. The key thing to take from that - if your engine needs a rebuild - treat yourself and have its capacity increased. There's nothing worse than spending money on your car only to have it returned in the same state it was previously in before the issue occurred.......and as Baz stated - in the grand scheme of having your engine removed, stripped, bored out, re lined with new pistons, bigger ims, etc. etc. the extra cost of having this done is minimal. All in all, another great visit to Hartech. There's a reason these guys win awards and it ain't through leaving a bunch of flowers on your passenger seat when the job's done. Professionalism at its finest. Now please, please, please don't quiz me about the stripped engines bodged by other engine rebuilders/failed ims upgrades/Gen 2 DFI faults/shoddy head machining by Porsche/etc. in there for repair :shutup: :grin: Just one other thing on the oversized engines, I'm sure Baz was saying the economy from these engines is improved but I was enjoying the experience too much to remember if that's what he actually said. Another :thumbs: for Hartech!

Hartech. Nice write up Alex, these oversize engines sound good. Hartech are no doubt the experts for 996 engines. Wonder what the 3.9 manual would be like? :thumb:

Do they have a 997. 1 3.8 under development bored to 3.9?

Yes they already have one done. In fact I think that may have been the 1st one. I think Baz was eager for me to try the 996s as I'm only used to driving mine.

Nice write up Alex :thumb: I`ll definately go this route when the time comes :grin: Did they have any BHP/torque numbers for these 3.7 and 3.9 upgrades :?:

They have their own in-house testing area with rolling road so I guess they must have but we didn't discuss it.

Good stuff, Alex. Do you have much experience of the 3.6 in standard form? I believe the 3.6 has quite a lot more lower-end torque than the 3.4 , so would be interested to feel how much more the 3.9 brings on top of the 3.6

No sorry.

No worries, thanks for interesting write-up anyway :thumb: If my engine needs rebuilding, I'll definitely go 3.9 (or even 4.0...).

Great write up! I wonder what the increase in engine displacement costs, over and above the standard full-fat rebuild? Why did they choose 3.9 as opposed to the 'S' spec 3.8? (or indeed 4 as per GT3 4.0...) Any increase in rev limit?

I think the biggest driver for that was availability of space and strength. Taking the liner diameter bigger takes a fair amount of support out the casting. There's only so far you can go before it potentially weakens it. I believe rev limit is same but didn't want to venture there for various reasons. I think the cost difference would just be variation in the two piston and liner diameters + any strengthening work on the blocks.

Interesting. Certainly worth considering if you're having a rebuild anyway. I don't experience the 3.4 as flat though. If anything it's one of the most linear, smoothest and rev happy engines I've driven. I wonder if there's a difference between cable throttle and e-gas for example. My previous genII 3.4 (Boxster Spyder) wasn't as nice as the 996.1 - I always assumed emissions requirements compromised it in places. What if anything do Hartech do to the engine management? Does the standard ECU and air flow meter cope with fuelling?

Great write up Alex :thumb: Is the 997.1 3.9 stroked rather than over bored ? As already concerns on the 3.8 bore being more susceptible to bore score than the standard 3.6 carrera 997.1? What power and price figures are they quoting ?

Pass.

When I looked at these recently there didn't seem to be anything with a longer stroke than the 3.6l, after that it was all increases in bore size. M97 3.8l 99mm bore 82.8mm stroke M96 3.4l 96mm bore 78mm stroke M96 3.6l 96mm bore 82.8mm stroke MC