LS3 Chimaera

[stefan1200]

Brummmie said:

Having done a bit of research into this, 32" primaries and 4 into 1 is what i found to be desired.
1 3/4" the best diameter, until you want big power, 600+ bhp.
Loss of torque might result in bigger than this before those power levels.

Almost exactly what I arrived at. Still weighing pros and cons for routing headers forward or directy down between engine and chassis (more difficult than in the Cerbera).

A lot of stuff for thinking.

[eff eff]

stefan1200 said:

@eff eff
This seems to be the configuration used for several conversions. Is the Y-piece and single pipe to the mufflers layout just for convenience or does it make no big difference power-wise in comparison to dual pipe layout? I was under the impression that dual pipes from front to end with X-pipe in between is the preferred setup for minimum power loss.

What are the experiences on here?

Cheers,
Stefan

The forward lay out seemed the easiest and most practical given the space around the chassis and it worked for the RV8. No power data yet but at one of the Growl meetings Per from Norway pulled 400 brake with a stock LS1 with a similar layout. My car is for the road not the drag strip and my early driving experience is there is more than enough power.

Edited by stefan1200 on Tuesday 15th May 11:57

[stefan1200]

Finally...

....and after having to wait much too long, I got my car back from the workshop last week with the conversion finished after 1,5(!) years. On the engine cover it says LS2, but, as mentioned before, it's an australien L98, so basically an LS3 less 200 ccm. The silver inlay covering the "Corvette" lettering were just for trying how that looks. I'm still not sure which covers to use. Please excuse the dirt on the cars, of course it was hissing down during my 100 miles journey home. Interesting experience, but managable! ;-)

I hope to be on the rollers soon to get the car properly tuned, right now it's running way too rich with some shunting at lower revs.

As you can see in the pictures, the exhaust is routed downward between the engine and chassis. I've seen this first on Christians (7 TVR) car and was very happy that the workshop did this too. For me it gives the engine bay a tidy look and the LS sits there as if it belongs there in the first place.

How does it feel? Of course, very very powerful! The lower part of the rev band still needs some tuning, but upon passing 4000 rpm it comes on the cam and is unbelievably fast!

It's weighing in at 1123 kg with a full tank after the conversion.

The TKO 600 gear change still feels rather stiff in first and second gear, but I hope with time and another oil change to the recommended GM fluid this will be getting better. I'm glad I chose the 0,82 fifth with the gearbox (thank you Brummmie!), 0,64 would definitely take the edge out of it. Still thinking about the 3,08 diff at a later stage. For now the 3,45 is fine with me.

Now one question for you guys with experience: The engine tends to stall when pressing the clutch pedal and coming to stop. Right now, I don't use any VSS signal from the gearbox, which is supposed to help. Are there any other options, or would the tune take care of it? I'm using a Holley 90 mm mechanical throttle with my LS1 PCM.

Thanks again for all your valuable input 2 years ago!

Stefan

[flyingdutchie]

I had the same problem when coming to a stop. Have the same engine in my Cerbera btw. What my tuner did was install of a throttledamper. It softens the sudden shut of the throttle and my problem was cured. A mercedes-benz part. It can also be found on 250-280SL's from the sixties. These engines were used in a lot of mercedes-benz cars. Also 70's and 80's.

[GTRene]

sweet...

more pictures won't hurt

[eff eff]

Stefan what bellhousing did you use for the TKO?

[Alexdaredevils]

Interested to see the exhaust manifolds please

[stefan1200]

Ok, folks, I promise to be back with pictures later, after having found out how to upload more than one! ;-)

@flyingdutchie
Thanks for the info with the damper. Might be an easy solution for the problem. A quick lookup showed that throttledampers were also used on Volkswagen VR6 engines at some time, so they should be easy to obtain.


@eff eff:
I use a QuickTime scattershield made out of steel, but weighing not more than maybe 20 lbs, IIRC. It meets some kind of SFI safety standard (might be a bonus in a GRP-body car!) and they claim that no further "dial indicating" is necessary.

Stefan

[GTRene]

you can upload more than one picture at the time by repeating the "upload an image" instructions.

after one is uploaded you close that program and then open it again like you did with that first picture and then again and again, open then upload then close that program and then open it again to repeat

[stefan1200]

Ok, here we go... though the chassis looks old on some pictures, it has no rust at all.

[900T-R]

flyingdutchie said:

I had the same problem when coming to a stop. Have the same engine in my Cerbera btw. What my tuner did was install of a throttledamper. It softens the sudden shut of the throttle and my problem was cured. A mercedes-benz part. It can also be found on 250-280SL's from the sixties. These engines were used in a lot of mercedes-benz cars. Also 70's and 80's.

I think the throttle dashpot was part of most Bosch K-Jetronic installations, too. All of my Saab 900 turbo's had one - which provided tons of fun fimnding the right balance between rpm dropping way below idle (and occasionally stalling) on shutting the throttle, and slow rpm comedown to idle by bending the bracket that held it... I like hammer/mole grip adjustable features

[Pete500]

Great job, but I would move the oil filter to another position and shield the engine sump and gearbox from exhaust heat. Per

[stefan1200]

Pete,

I've seen that you also wrapped part of the exhaust on your car. Mine is wrapped a little bit beyond the sump, you think it will still heat up too much?

[SteveSPG]

Stefan

my ls griff ran exhaust close to oil filter. I wrapped the filter in heat mat, after 3000 miles, it was fine.