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Head upgrades

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by losh1971, Feb 27, 2020.

  1. losh1971

    losh1971 Well-Known Member

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    Starting to think about the next engine mod I want and it's the heads from my spare engine. Few questions though. I need to know how much I can shave the heads before i have preload issues. Most of the rockers have around 1/3 - 1/2 a turn but some have 3/4. How much can i safely shave off without looking for new rods? Also I don't want to go sick on comp, incase i decide I want boost down the track. Other question is on porting what should I tell the bloke I want as i don't want to lose much bottom end. Should I have anything done to the intake manifold or just leave that? I'm sure I will have more questions as I get closer to dropping the heads off.
     
  2. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    I read somewhere weeks ago around 30 Thou before you start needing to change the lifting rods to allow tolerance .
    You doing the work or getting the mechanics to do it bar the milling of coarse.
     
  3. losh1971

    losh1971 Well-Known Member

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    Merv Gray will do all the machining. I may or may not rip the heads off and refit haven't decided. Depends on how much time i have. Me doing the job three days no ute. Mech does the job i can drop it off before work and pick it up the same day.
     
  4. vc commodore

    vc commodore Well-Known Member

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    I've sent you a message with the details of a mate, that has been involved with speedway engines for 30+ years...He currently has a V6 powered wingless sprint car he built himself.

    Hope it helps you
     
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  5. afstruct

    afstruct Well-Known Member

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    [QUOTE="losh1971, post: 3074945, Also I don't want to go sick on comp, incase i decide I want boost down the track.

    Boost = supercharger?

    Was told = ok ls1 verious v6 but same principles = spend money on forged bottom end and increase boost = better than spending heaps on heads , although it would ultimately I think depend on the heads efficiently along with a hole lot more variables including the cam
     
  6. losh1971

    losh1971 Well-Known Member

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    Boost yeah SC, probably doubtful if I will ever go boost unless I fit a small SC14. The cost is too great for anything decent. I'm not looking for cam at this stage as the front end and sump has already been off once. The Mace rockers are doing a pretty good job. I guess could get a cam with more duration as I'd have to go shorter rods if I went with a larger cam, which defeats the purpose of 1.9 rockers.
    I'm thinking heads are the next "logical" thing, even though nothing is logical even a V8 for a DD, in the end it's all wasted money lol.
    With NA I can go some extra comp, and a freshen up of the heads will help ensure they are working as well as they can. Plus the benefit of reshaping the valves and seats and some mild porting. This would be something I'd do even if I did eventually go boost. Valve springs are probably a tad soft anyway for my hi ratio rockers.
    The thing I do like so far with the mods I have done is economy wise it has improved by around 3lph, and yet I probably have an extra 30kw more than what I started with when I bought the ute a few years back. I'm thinking head upgrades will increase the KW but won't sacrifice economy.
    Talking to the dyno tuner and he reckons I am maxed out on the intake side. He said if I go anymore HP I may need to address the restrictions I am seeing at WOT just before it peaks. Thing is I was of the understanding that my current set up even a standard V6 TB wouldn't be a restriction and I am running a 304 TB, which takes me by surprise as I am not sure what to change in order to increase the air that comes in.
     
    Last edited: Feb 28, 2020
  7. woteva

    woteva NEED 4 SPEED

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    Need more throttle ?
    Just add another.

    bodys (3).JPG
     
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  8. gtrboyy

    gtrboyy Well-Known Member

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    Think he means your manifold is next restriction..volume or distribution issue
     
  9. losh1971

    losh1971 Well-Known Member

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    Yeah not sure because @delcowizzid posted some results of his and he has stock manifold. What are you thinking I need to do? I can port the manifold but you lose torque I am lead to believe, which is kinda pointless on a DD. No use me trading bottom end for extra HP at 4k. I rarely get it over 3k.
     
  10. gtrboyy

    gtrboyy Well-Known Member

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    TBH not sure if there are cost effective mods left...you either go turbo or go all in naturally aspirated.

    Burnout fiends do twin throttles while back in the SC days peeps were adding volume to manifolds.

    Think the Delco engine was tuned/built to serve different purpose like speedway(?)

    Years ago a mate of mine did the heads for v6 vengence...went 3-4 tenths quicker down 1/4 yet showed only a small gain in torque on dyno.
    Apparently was a tonne more on street despite being clapped out stocker engine,leaking rear main stock intake & biggest off the shelf cam Scotty could jam in it.

    Basically are once cammed with suitable cr manifold will hold them back.
     
  11. losh1971

    losh1971 Well-Known Member

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    I think some head work will benefit low and top end. Given it probably has some miles on it the valves would benefit from a valve grind plus something shaved off to also help get some more compression. I am considering a cam with stock lift but some extra duration. But that will depend on if I do the work or the garage does. I want the mech to disco the balance shaft like I requested but he failed to do during the overhaul. I reckon even just stopping the engine having to turn it will actually increase HP, even if only marginal. On a race bike we take off any gear that the engine spins, plus we reduce any weight that we can that the engine needs to drive, even dropping down a chain thickness to help HP at the wheel. Not sure if same applies to cars but on bikes any weight the engine is not driving is equivalent to 100x that in actual weight. so essentially 10 grams off the crank is equivalent to a kilo on the bike frame, IIRC.
     
  12. vc commodore

    vc commodore Well-Known Member

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    Honestly Losh, I'd be thinking long term on what you actually want in the end....You've been talking S/C....Do you want S/Cing, or naturally aspirated....By thinking long term results, it will enable you to do thinks once and not throw money willy nilly on patch up areas.

    ie, Heads/compression....Shaving heads, porting heads are done to suit what you are going....S/Cing requires less compression, therefore the heads only need a skim....Bumping the compression, means more shaving.....Then you have the porting to suit what you're chasing.....Get the lot done all at once....Saves too and froing to the machine shop.

    This is just the start....Also don't think I'm having a dig at you.....I'm thinking of long term and the all mighty dollar that's involved....Unfortunately people get sucked into one area, spend coin there and all of a sudden, they need to upgrade that area to suit the next step they take.....

    Worth considering
     
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  13. losh1971

    losh1971 Well-Known Member

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    Yeah and this is what I need advice on. I definitely want to upgrade the heads that's on the cards. But what I do to them I really don't know. I am pretty sure a reshape of the valves and seats is a no brainer, as is some mild porting. I don't really know how much to shave off the heads I wouldn't know if 10 thou is a lot and yeah I want to keep my options open that if I decide I want SC then I can. I may be happy enough with the head upgrades and will stay N/A, especially with some 3.45s and a shift kit.
     
  14. afstruct

    afstruct Well-Known Member

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    It's a daily save , save ,save= keep the exhaust and fit / mod a l67 .
    In a daily this type of supercharger = a grin from ear to ear )
     
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  15. losh1971

    losh1971 Well-Known Member

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    I'm having fun working with the L27. At this stage I am happy to keep going with it for a while. I have my eye on a SC14 which I should be able to fit myself. I'm just waiting for the price to be at what I feel it's worth. So far full kit with brackets is $500 but it was $800 a few weeks ago. I'd be comfortable at $300 that way if I decided to never fit it I won't be much out of pocket.
    I still have to think if I want to sacrifice economy for a few extra KW. The heads and re-gear will only help economy, I'm pretty sure so it's a no brainer.
     
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  16. Hivisibility

    Hivisibility Member

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    Dpepends on your determination... I know you are in Tassie, but take a holiday to the mainland and grab yourself a L67 and go from there... will be much more value in the medium/long run and reality you just need to change some wiring/Fuel pump and Memcal... and your smile will go for miles. Young fella does this sorta thing drives 28 hours there and back to get what he needs at the right price... makes a few days of it with his lady and mate.. has the best time and has the quickest P=plate car in the area at an all up cost of maybe 7K (VY S_Pac ute in black, 10 psi L67, 5 sped T box, 3.45.... ) He's owned 12 or so commodores since getting his Ls and hes just turned 19...everything he does is done on a budget and usually works out.
     
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  17. losh1971

    losh1971 Well-Known Member

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    So been thinking and I am thinking more about economy over HP. Plan is to still upgrade the heads but go no further on engine mods. I reckon I will get some gains with fresh heads, mild porting and valve reshape. I am pretty confident that I will be happy with the end result.
    3.45s and final stage shift kit is on the cards for this year as well. I believe as far as gains and usability go this is around the limit, unless I want to use more fuel, which I have decided I don't. Gonna book in for a shift kit or 3.45s soon as i hear from the trans tech. I'm just undecided on which first. I'm hoping the trans builder might help sway my decision.
     
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