Piper do some mild regrinds, for longer duration, high lift cam you'll have to for blanks.

 

Hi,

Thanks for your input

This is the info I have found on Schrick cams for the NB

Intake 256°, cam lift 9,5, valve lift at TDC 1,3, valve clearance 0,25
Exhaust 256°, cam lift 9,5, valve lift at TDC 1,3, valve clearance 0,35

Another option is to have a Mk2 Exhaust cam reprofiled, these have 8.89mm lift and a duration of 210 degrees at 50 thou lift.

I think that 100 thou (2.54mm ) could be ground off the base circle which would result in 11.43 mm lift

My Supertech valve springs are rated for 12 mm lift

Tomei NB inlet cam 10.8mm lift, duration at 1mm lift 220 degrees

Kelford inlet 10mm lift, duration at 1mm lift 230 degrees

Does anyone know the figures for the Blink Cams for NB ?

Does anyone know the figures for the Piper NB regrinds ?

Below is info From Maruha for BP

Duration Lift HLA Base diameter IN 252° 10.0mm Special lifter needed 33.0mm EX 256 10.0mm Special lifter needed 33.0mm

Here is a fun picture of two camshafts,

A modified Camshaft for an 1934 Austin Seven which has had 50 thou ( 1.27mm ) ground off the base circle, note the undercut core.

And a standard NB BP4W Exhaust cam.

Note 20p coin for scale

 

Personally I don't look at regrinds.

On the MX5 core they can't get the duration and lift required for the possible gains - if they say they can the technical data proves they can't.

I use CatCams for all of mine and have various profiles that I use, the quality is always 100% and the gains are always remarkable. I've got a CatCams order going in at the end of the month - get in touch and I'll happily discuss profiles [as a hint, you want more duration than those listed].

Daniel

 

Hi Daniel,

Thank you for your input.

I was wondering if more duration would be benificial on the four valve head.

I still need the car to be roadable IE wife must be able to drive it,

I have port matched the head to inlet plenum removed casting flashing from ports , unshrouded the valves and opened up the exhaust ports to match the gasket size,

I have still to match the chambers then skim the head to bump up CR as well as get the valves and seats reprofiled.

For what I am doing I am hoping to make gains with lift rather than Big valves.

The Austin Seven Camshaft in the picture has 6.83mm lift compared to the Mazda exhaust at 8.7mm

I am having another Austin Camshaft reprofiled to give power from 3500 to 7000 rpm on a side valve engine !

I will contact you through Ardler Automotive

Regards Dickie

 

Hi Dickie,

It's difficult to comment without giving away too much but duration on a 4 valve head makes all the difference, with a 4 valve head the overlap can be controlled and tuned better than a single cam engine - this makes things ALOT more achievable that the older style engines.

The right profile can give you a stock drive below 4k but a huge difference from 4.5k to limiter.

Daniel

 

Watching this topic with interest as one of my future buys for my mk2 1.8 along with a ported and flowed head will be some decent cams to compliment my current Itb and megasquirt set up.

I have been advised by a couple of sources on profiles but need someone in the know to advise, blink suggested the piper regrinds which i'm not sure will do enough (approx 256 duration) and others have suggested ones ground from blanks, something like pipers 285's. I want to retain decent idle and not lose any more low down torque(the itbs do lose a little low down over standard vics manifold).I also don't want to move the power into a silly upper rev range, 6.5, 7k to make peak power is just fine. I know i want my cake and eat it

 

Hi All

I am expecting the rest of my valve train parts in from USA in the next couple of days.

I will be re starting work on the cylinder head once they arrive.

( I have been painting the garage floor instead of playing with engine )

I will see how high I can make the compression ratio my starting baseline is 10.5 to1 with Mk2.5 block headwork and deshrouding will have dropped the static CR, so bowl matching followed by a head skim will see it up around 12.5 to 1

When I have finished the head I will do a bit more research into camshaft choice.

David Vizards port and flow test book and Des Hammill how to choose camshafts are good bedtime reading.

Cheers Dickie

 

Hi Petrolheads,

My Mk 2 cylinder head is away at race engine builders for 60 thou skim, new bronze valve guides and multi angle valve job.

I have been in contact with Piper cams, they are interested in seeing if the BP4W exhaust cam is suitable for a regrind to inlet spec.

They think a 285 profile will be possible to grind on the exhaust cam.

Watch this space !!

I am using Mazda Motorsports Shim under bucket camfollowers which are taller than the standard ones which will allow a reduced base circle on the cams.

Cheers Dickie

 

I'm a big fan of NA tuning and love learning the technical details of the effect of different cam durations and lift etc. Thanks for the recommended reading, I might just add those to my Christmas list!

Sounds like a very interesting project you are doing, thanks for sharing and it would be great to see more. Following with interest :thumb-up:

 

Even with a 4 valve head, thinking you can drastically increase duration (without other changes such as higher compression pistons etc) without significantly losing low down power is a massive mistake in my experience.

 

Hi StavFC.

I agree with you for a standard low compression Mx5

If you read a bit more of what I am up too my base compression is 10.1 (Mk 2.5 bottom end Mk2 port matched head) unshrouded valves and head polished and balanced chambers then a 60thou head skim will put me above 11.5-1 which is the right area for a 285 duration cam.

Regards Dickie

 

Hi Petrolheads,

Happy New Year.

My head has come back from being skimmed , bronze valve guides fitted, multi angle valve seat reface,

Head re assembled and found to be 12-1 static compression ratio, Cams away to way to Piper for regrind.

I will report back with their input.

Cheers Dickie

 

What pistons do you have?

If using any stock pistons then you've calculated something incorrect. 12:1 static compression ratio isn't available with stock pistons.

What is your combustion chamber volume from cc'ing the head?

Daniel

 

Hi Daniel,

I measured 45cc in the chambers using a burette after head skim.

Original figure after head polish and deshroud 54cc

Piston dome displacement measured at 8.8cc

.6mm for head gasket

negative .6 for deck height

Bore used 83mm

Stroke 85mm

Bottom end is a 1840cc 10-1 Mk2.5

Head is from a Mk2

I am afraid that I used an online calculator for compression ratio.

The real figure will be a bit lower because when I did the piston crown displacement I filled the ring lands with grease to stop the windscreen washer fluid I was using going past the rings.

I actually got 11.74-1 and 12-1 using the online calculator at race-cars.net

I have just re done it using 1.2mm for gasket and deck and came up with 11.74-1

Regards Dickie

 

Hi Petrolheads,

I now have the reground cams back from Piper.

The Cam figures are

Duration 276 deg,

inlet lift 10.21 mm,

exhaust lift 10.16 mm

inlet lift at tdc 2.23 mm

exhaust lift at tdc 1.93 mm

These figures have been ground onto a set of Mk2 1840c cams for use with Mazda motorsports solid shim under bucket cam followers.

Regards Dickie

 

Sound good Dickie, well done for finding what looks to be an excellent solution, look forward to following the continued progress :thumb-up:

Out of interest were those ground from inlet and exhaust cams or two exhaust cams?

 

What are the durations at 1mm of lift (some might quote duration at 50thou)?
Does it give overlap duration and centres?

Sounds ok so far but the above information will be more revealing

Dan

 

I have now sent the head and cams to have the shims set up by the race engineer that I use.

my progress is slow at the moment.

I am waiting for a set of O/S crank shims from Mazda to reduce the end float I suspect they are coming from Japan.

Regards Dickie

 

Any News/ Following this with interest.

 

Hi Petrolheads,

I have spoken to the the engineer that is doing the shims for me and he is waiting for a delivery to come from Piper with some parts for other engines, He is busy building race and rally engines at the moment, my job is a fill in slow time for him.

Mazda does not have any oversize thrust washers in stock so I will have to go with the standard size and have one of the old thrust washers ground down to use as a shim on the forward side of the bearing away from the clutch thrust.

Cheers for your interest

Regards Dickie

 

Hi Petrolheads,

If anyone is still following this slow moving project her is an update.

The head is now back with all the shims fitted, I need to give it a good clean then lube it all with camlube then it cam be fitted to the lump and have the cams set up,

I have just bought a Meite ECU to run it with which I am fitting to my RS Ltd so that I can learn how to set it up before I try and run the High comp Cammed motor.

Regards Dickie

 

Cheers for the update, watching with interest!

Russell

 

Hi all,

Slight hiccup in progress,

I have broken the gearbox in the working car so I need to put a spare gearbox into it, at least I have got some old carpet to lay on while I am underneath it.

I will replace the clutch + thrust and pilot bearing while its apart.

Cheers Dickie

 

Hi all,
Slight hiccup in progress,
I have broken the gearbox in the working car so I need to put a spare gearbox into it, at least I have got some old carpet to lay on while I am underneath it.
I will replace the clutch + thrust and pilot bearing while its apart.

Cheers Dickie

How annoying hey Dickie. I know how you feel with the odd hold up by unrelated issues.
I have just pulled out a working 5 speed box from my R LTD if it's of any use or help. Just drop me a pm if so.

I have the similar piper cams in my R Ltd with one of blinks race heads. It's on the dyno on Wednesday so we will see the gain altogether then.
I'm following yours with internet bud! Looking forward to the update.

 

Hi Ryan,

Thanks for your input and offer of Gearbox.

I am in the process of installing a 2004 box into the car at the moment, I had to swap speedo drive and a sensor from the old box, ( the dead box has a rattle when you tip it end to end something is loose inside it) Fifth gear went ping going over the Exe at Topsham on the motorway.

I still drove to Beaulieu and back with it, I just used second third and fourth gear a first and reverse started to grind as well.

I will look forward to seeing your Dyno results ( which rolling road do you use )

Regards Dickie