Head Work Advice

[BlueBolt 156]

Ok, so I've had a gti6 conversion completed by miles with the audition of some Jenvies and an Omex 600 system to run it all...

 

What I should have done is get it cam'd and had the head rebuilt at the same time to allow for something rather aggressive on the cam front to be put in... But due to having a limited cash flow and having quite a lot of work already being carried out, I didn't...

 

So, what would the suggestion be for me to do...

I want a heavily aggressive can, but am guessing in order to get the best out of a big cam set I need to upgrade my valves, which in turn would (again guessing) lead me to needing to have the pistons worked to allow for the extra movement...

I say guessing a lot as I'm picking up on things I've been reading recently in a few of the build threads.

I guess I'm looking for around the 200bhp mark, currently running 175 from the above modification...

 

I need to be doing all this as cheaply as I can, although I cannot honestly see me actually doing anything or some time (financial hindrance) I wanted to get some advice and see what people thought. I have already read through a lot of the build threads and seen what's been done. And I am also aware that I don't only want to be taking the cam out, putting a new one in and getting it mapped with the vernias. I'll be looking to have the valves re-seated and new bits thrown in to make sure the head is good for a whole to come!!

[welshpug 1,680]

as you noted, the most important aspect of camming these engines is valve clearance, notably the lack of any in the standard pistons.

 

you don't need to change the valves, though depending how wild you go you may need to change the springs.

 

 

I don't think you need silly cams for 200 bhp, which means you can save pulling the engine apart if you choose the right cams, something like a Newmans PH2, or some peterT regrinds, not much else is safe in the standard pistons.

[BlueBolt 156]

Do the pistons already in place get taken out and played with?? Or do I get aftermarket jobbies?? I know it's not going to be a cheap thing to be doing no matter what I do... But am thinking that as I'm going to do it I may as well go for big and aggressive as hell as I only want to do it once!! Lol

[Miles 331 1 Cars]

As you never know if the heads been skimmed or not it's hard to say what Cam's you can or cannot fit, Safest way but expensive is to do a dry build to check the clearance.

I know the old group buy of Peter T cam's is being done so I'd watch out for the result's as I've yet to see any in the UK

[BlueBolt 156]

I know the old group buy of Peter T cam's is being done so I'd watch out for the result's as I've yet to see any in the UK

 

I remember seeing them on the group buy a while ago... Looked to be at a good price too...

Is the standard clearance that fine that a skim would make the life or death difference??

If so... BLOODY HELL!!!!!

[welshpug 1,680]

pretty much the case with many of the of the shelf grinds available.

 

a few routes,

1. leave as it is as its quick enough.
   
2. risk cams in a standard unknown engine.
   
3. pull engine apart to check pistons, get pistons machined to accept relatively mild cams.
   
4. pull engine apart and fit shiny pistons.
   

[BlueBolt 156]

pretty much the case with many of the of the shelf grinds available.

 

a few routes,

1. leave as it is as its quick enough.
   
2. risk cams in a standard unknown engine.
   
3. pull engine apart to check pistons, get pistons machined to accept relatively mild cams.
   
4. pull engine apart and fit shiny pistons.
   

 

Ok, 1 is the option that is being done, but only for now!! lol

2 is a no-go...

3 and 4 are the ones that are the way forward I guess... Then if I go down the fourth route I guess it's a complete engine rebuild time as it may as well be done while its all apart???

[Miles 331 1 Cars]

Don't forget a remap afterwards

[BlueBolt 156]

Don't forget a remap afterwards

 

Yea already guessed that bit even with a subtle regrind cam, be able to get the rollers to set up the verias too at the same time...

[petert 616]

Sorry if I missed something, but aren't you having gearing problems? If so, I'd be getting that fixed first before attempting a cam change, as it will only make the situation worse. If you're still using the standard 1.9 box then you're really missing out on something.

eg

http://www.youtube.com/watch?v=EWub65Q-rNQ

Edited May 6, 2012 by petert

[BlueBolt 156]

You're correct about the use of the 1.9 box, but if I added a set of cams that kick in from 2k then the 1.9 box will be much more appropriate as the engine will not big down when changing gear and hitting the 5k mark when changing from 7500ish... The added bhp and torque will also allow me to not be topping out at 124mph like on the 1.6 box...

 

What box or hybrid components are you using in that clip??

[welshpug 1,680]

1.6 box should give you nigh on 140 flat, 1.9 over 150! MI box right between them in 5th.

 

 

gear speeds @ Phase2 redline of 7200

('box/FD) 1st 2nd 3rd 4th 5th

 

1.6/1.6 36 64 88 112 138

 

1.9/1.9 45 71 97 123 151

 

mi16/mi16 38 59 86 113 144

[Anthony 1,003]

Cams will typically move the power band upwards, not downwards.

 

I'm not sure what the rev limit is set to on yours, but on a 1.6 box you'll run out of revs in 5th around 135-140mph or so. Is that not quick enough?

 

By all means spunk your money on cams and headwork, but I'll back up with Petert is saying in that you're wasting your time keeping that gearbox on there as 1.9 boxes are ill-suited to 16v conversions. Put a shorter ratio gearbox on and it will transform the character of the car, and whilst it possibly won't be any quicker against the clock, it will feel so much faster and more lively.

[BlueBolt 156]

whilst it possibly won't be any quicker against the clock, it will feel so much faster and more lively.

 

I don't like taking her much over 120 (obviously on private roads!! Lol) to be honest!! So yes, thats plenty quick enough!!

That comment brings about someone's signature, can't remember who's as I don't see them from my phone, but it reads "it's not how quickly you drive but how you drive quickly!!"

I'm aware that I need to sort the ratios out... Hence my wanted post, and also tryin to source a 1.6 box (steal off a mate more to the point lol)...

Also, knowing the ratios and top speed of a 4.4 CWP in a 1.9 box, what's the same for the 4.8??

 

This is where the oposite opinions come out on here, I mentioned something about the gearbox on another thread and someone said I should worry about the output before the gearbox... Lol

All good advice in their own way... It all needs to be done over the years lol

[petert 616]

That clip is probably a bit extreme as it's a 1.9 gear set with a 4.75 cwp. I have no idea what you're using the car for, but hazarding a guess, I'd suggest you take it back to Miles and ask him to fit a 4.06 cwp into your existing box, along with an LSD if it hasn't already got one. That is money spent wisely.

[Paul_13 212 1 Cars]

I'll be packaging cams tomorrow, sorry for the delay been really busy of late.

Group buy is still open, if you have a spare inlet cam let us know and get it sent over if your interested.

[BlueBolt 156]

I'll be packaging cams tomorrow, sorry for the delay been really busy of late.

Group buy is still open, if you have a spare inlet cam let us know and get it sent over if your interested.

 

Money is a big problem with this at the moment... Else I'd be well up for it!!!!!

 

What do you top out at with the 4.75 in the 1.9 box??

[BlueBolt 156]

along with an LSD if it hasn't already got one. That is money spent wisely.

 

Looking at a gripper diff at the moment, managed to source them new for around 450 for cash...!!

[Anthony 1,003]

What do you top out at with the 4.75 in the 1.9 box??

118mph @ 7200rpm

 

Be careful not to go too far, as given that it's a road car still primarily you'll simply make it unusable on any long journeys if you're not careful. You'd be doing around 5000rpm at 80mph with that 4.75 FD, which is ridiculous.

 

Personally, the absolute shortest that I would go is a 4.4 FD, which gives 126mph @ 7200rpm and a 80mph cruise at 4600rpm - even that does get very tiresome on a motorway, especially if you have a loud boomy exhaust. To give you some idea, that's very close to the current 4th gear on your 1.9 box - could you cope with that as your 5th in effect?

 

I agree with Peter in that a 4.06 (1.6 GTi) final drive is a good match for a typical 16v engine that's used on road and track - short enough to keep it on the boil and make it feel lively, but long enough that you've still got sensible cruise rpm's in 5th. To back that up, that's a 4200rpm @ 80mph cruise and will top out at 138mph @ 7200rpm.

 

Also, as Peter says, a decent LSD will make more difference than another 10-20hp will.

[harryskid 193]

May be you need this !

 

[BlueBolt 156]

Really??? This is coming into more threads now?? Lol

[DrSarty 100 1 Cars]

Sorry - am I missing something?

 

In your opening post you mentioned a GTI6, with Omex ECU and Jenvey ITBs, and you're getting 175bhp? That's an 8bhp gain on standard.

[harryskid 193]

DrSarty made a good point there some thing does not seem right !

[welshpug 1,680]

DrSarty made a good point there some thing does not seem right !

 

sounds like it may just be classic comparing RR's with other RR's...! if a known healthy engine wasn't tested immediately prior to that run you can't take that figure as gospel.

[BlueBolt 156]

I'm waiting to hear on news of a standard gti6 being run on the same rollers over the next week or so to gauge the output, the suspicion is that they are reading out with low figures, but with nothing to gauge it against at the moment I cannot comment really....

 

The only thing I know needs to be done to the engine in any way at the moment is a bit of work to the head as the lifters are a little tappy... By sure how much work is involved in this though or how long I'm able to leave it a little tappy before I have to get the work done there and then???