VVT on an LSA

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Discussion

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
Have come across this "simple" conversion for LS engines to retrofit variable valve timing http://www.hotrod.com/how-to/engine/hrdp-1007-gms-.... Looks like it could be an interesting mod to help with drivability on higher power specced cams.

What are peoples thoughts on it?

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
you do realise why VVT was never introduced after their aborted 48v efforts?

VVT adds complexity for little to no benefit. Want more power at the top end, fold the rear seats forward.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
wait, ffs VVT not quad cam heads.FFS. Well look, fold the rear seats down for an extra 5mph top end

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
Erm, the new LT platform has this as standard. Specifically the LT4 in the new CTS-V hence the retrofit comment.

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
stigmundfreud said:
wait, ffs VVT not quad cam heads.FFS. Well look, fold the rear seats down for an extra 5mph top end
(mapped)?

ArnieVXR

2,449 posts

182 months

Monday 22nd December 2014
quotequote all
I think it's been around foursome time. Remember seeing a marking LQ4 (or 9) with it fitted. No one seems to be that bothered with it. Not sure why.

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
I guess I'm going to actually have to join up to ls1tech as they might know more. Something like this would be right up ringrams street unfortunately.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
look at the figures they dont seem groundbreaking for the additional reliability concerns.

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
Not looking at this necessarily just for power gains, more lower end drivability with a more aggressive cam means you can go for more top end power yet still have a nice idle.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
at the expense of complexity, a much easier trick is to map the throttle position

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
Still not going to help low end torque though is it?

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
is that something thats really missing? I have a big v8 with multiple cams and variable timing. It also has a throttle map button, whilst i am sure the vvt does its job and makes its the throttle map that makes the hugest difference

do you really need a few more ft lbs down low?

R8VXF

Original Poster:

6,788 posts

114 months

Monday 22nd December 2014
quotequote all
I don't know tbh, this is my first V8 and haven't modified it yet. Was hoping for some collective wisdom smile

I do drive my car round town a lot so really need the low speed to be nice but would like big top end numbers.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
first thing i would do if and when i convince ringram to sell me back an efi at 2006 prices will be to remap the low down throttle map, next time am down in the beemer in green park will give you a demo of the difference a throttle map makes (not done it on the vette so no point

KMud

2,924 posts

155 months

Monday 22nd December 2014
quotequote all
I have bumped the spark about +10 degrees in the low airflow/low rpm regions of the spark tables and it really beefed up my low end, possibly too much. I may dial it back a little. VVT would be lovely, but...

ARAF

20,759 posts

222 months

Monday 22nd December 2014
quotequote all
R8VXF said:
I don't know tbh, this is my first V8 and haven't modified it yet. Was hoping for some collective wisdom smile

I do drive my car round town a lot so really need the low speed to be nice but would like big top end numbers.
I've just had the AFM (displacement on demand) bits stripped out of our engine, and replaced with conventional parts. Not quite the same, but when you think that an LS3 red lines at 6500revs, yet an L76 redlines at 6k revs, then GM obviously thought it was a weak spot.

Keep it simple.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
KMud said:
I have bumped the spark about +10 degrees in the low airflow/low rpm regions of the spark tables and it really beefed up my low end, possibly too much. I may dial it back a little. VVT would be lovely, but...
you on cable or electronic tb? it did seem very weak timing low down but I suppose it helps keepin itt smooth if you have an etc try mapping the ram rates but dont go silly and never set any of it to 100%

Sarge 4x4

2,371 posts

204 months

Monday 22nd December 2014
quotequote all
R8VXF said:
I don't know tbh, this is my first V8 and haven't modified it yet. Was hoping for some collective wisdom smile

I do drive my car round town a lot so really need the low speed to be nice but would like big top end numbers.
Just chuck it at WP and let them sort it.

I am very happy with the result. smile

KMud

2,924 posts

155 months

Monday 22nd December 2014
quotequote all
stigmundfreud said:
you on cable or electronic tb? it did seem very weak timing low down but I suppose it helps keepin itt smooth if you have an etc try mapping the ram rates but dont go silly and never set any of it to 100%
Cable. I'm not sure what point I was making...I guess just if it's weak around the idle area, it may be beefed up with spark unless it's already maxed out with a donkey dick cam. I'm not sure I lost much/any smoothness since that seems mostly related to transitions from base spark to the high/low octane tables, but it's more eager (straining at the leash). I am on LS1B where life is simple...

If it's a big engine with a big cam, and we're talking more optimising power through the rev range I could see VVT being worthwhile.

stigmundfreud

22,454 posts

209 months

Monday 22nd December 2014
quotequote all
we have dual lobe cams whats not to love about keeping it simple, though it would be great to scream vtech just kicked in