Camshafts

[Kieran]

I am thinking about installing some TODA Racing High Power Profile Camshafts but am not sure of what the best type and lift would be if im going to eventually add an ITB setup
any help would be greatly appreciated

[sprsta]

hi Kieran
welcome to the forum

it all comes down to what you want to use the car for
will it be a daily driver in lots of traffic jams?
do you want to take it to the track every weekend?
do you want a 12000 rpm redline?
will you use an aftermarket ecu?
how much head work do you want to do?

mine was terrible with the stock ecu at idle/low revs
that was with 264 duration 9.3 mm lift hks cams
link changed that though (900 idle)


2low2c has todas in his at the moment he will have plelty of info on them

you could also do a regrind, that would be cheaper than new a set of todas

[Euen]

Hi Kieran

How refreshing to read of someone else with plans for normally aspirated development.

Whatever cams you choose, you will need an after market ecu to get the best from them. I am assuming that as your car is a 98 NB, that you have the BP-4W head. This means you have solid lifters. For some of their cams Toda recommend using their shim-under lifters as well.

I agree with sprsta that your choice will depend on your planned use for the car. I am using Integral (http://www.integralcams.com/) stage 2 cams in may Targa car and they are reasonably friendly at low revs. In hindsight I may have been better with stage 3 though. I am not using ITBs at the moment but they are something that I am looking at for the future.

[Kieran]

My plans are for a daily driver (maybe the odd track day) with alot of low end torque and i dont mind sacrificing my top speed to get this just so long as i dont use forced induction because i think N/A really shows what a car can do cause anyone can go fast with a turbo or supercharger not to say i dont like forced induction i mean who could hate the sound of a turbo spooling up or a superchargers whine but its just that N/A is my preference
I will be running a aftermarket ecu otherwise performance cams are a pointless expense but ultimately once i have done all the head work i want to run a full itb setup

Also does anyone know where i can get a good port and polish job done around auckland?

The thing that confuses me with camshafts is the different durations and lifts if im keeping to N/A would it be better to have a higher or lower duration because i saw a Toda set with a duration of around 304 10mm lift what does this mean
And i will most likely have to use Todas inner shim kit to be able to fit these camshafts

[Euen]

If you are looking for something to use in a daily driver then you don't really want to go too wild. The more aggressive the cam the less torque you will have at the bottom end and that will make it difficult to drive around town. Looking at the various options from Integral, 304 looks pretty hairy.

Have a look at the options for "1.8 Mechanical Lifter Cam Profiles, 1999-2001 engines" here http://www.integralcams.com/miata.htm

With regard to the specs of the cam, duration is only one factor to consider. The timing of the opening and closing also need to be considered, and as you have mentioned, the lift. Once you get close to 10mm lift on the BP head you run the risk of the cam lobe hitting the head casting on the edge of the lifter holes. This requires some careful removal of metal around the top of the lifter hole. If you are getting your head done then this would probably be quite easily done but care is required to ensure that the edges are properly finished to ensure that there is no damage to the lifter.

[Kieran]

Ok i see what you mean so the stage 3 cams would be as far as you can go without removing the metal around the top of the lifter hole

Stage 2 257° 217.3° .370" (9.40 mm)
Stage 3 263° 223.9° .385" (9.78 mm)
Stage 3.5 266° 227.5° .395" (10.03 mm)
Stage 4 274° 235° .395" (10.03 mm)

[Euen]

I got away with stage 2 but it is pretty close. It is one of those things you would need to check before final assembly (or before you get your head work done). Then afterwards you will have to re-shim the lifters unless you get your head guy to do it for you.

[Kieran]

If you don't mind me asking how much did your stage 2 cams from integral cost and also what kind of performance did you get out of them

[Euen]

They were USD795 plus freight and customs etc for the pair (about 2 years ago). Not sure what they are charging now as the guys running Integral sold out to another company (Megacycle Cams) so you would probably need to check and see what the current prices are. Megacycle seem to be maintaining the Integral website and all their contact details are there. From what I have seen on miata.net, the Megacycle people are quite approachable so drop them an email.

[Habanero666]

Ahhh yes, Normal aspiration. The expensive way to go slow

Make sure to get all your head work done by someone highly recommended but most importantly REPUTABLE.

Euens BP powered TG sports goes really well, as I have seen this vehicle on Targa NZ flyin! ( Giday Euen )

The BP engine is very good in terms of flow, high lift camshafts are your best bet, just watch your duration unless you want a clutch riding slug down low!

Adjustable cam gears will make a massive difference with fine tuning to unlock all the power the upgraded camshaft profiles have to offer.

ITBs will require high port velocity so big ports are not the direction to head (excuse the pun), a 3 angle valve grind IS ESSENTIAL if you are tuning N/A as every little bit you pick up along the way counts!

I would be concentrating on building a strong, well breathing, high reving engine run with good engine management.

Its not too good to have a car just not fast enough!

Oh yeah, just remember a fast N/A engine makes an excellent starting point for a FI engine

Jim

[Euen]

Hi Jim. Thanks for the complimement. Now I just have to keep it on the black stuff.

[Kieran]

Ahhh yes, Normal aspiration. The expensive way to go slow

Haha so true
thanks for the advice Jim

just watch your duration unless you want a clutch riding slug down low!

What kinda duration do you think would be good with itbs?

[Habanero666]

Ahhh yes, Normal aspiration. The expensive way to go slow

Haha so true
thanks for the advice Jim

just watch your duration unless you want a clutch riding slug down low!

What kinda duration do you think would be good with itbs?

The true crux of the dilemma is: "what length trumpets will I base my camshaft profiles around?". This is something often overlooked by "tuners" and plays a huge part in the power delivery! (Well atleast in my opinion ).

I would say the profile around 266° 227.5° (type 3.5 I think is the above camspec you guys previously mentioned). Although I would tend to keep the exhaust valve open a little longer, from experience.

The advertised lift looks nice at around 10.00mm ( I say advertised here, as the actual figures are only exact, when it is all set up with the cams and HLA pumped up or lifters shimmed, which ever head you choose to tweek, valves all installed, engine lubed and ready to go!).

These numbers should provide good cylinder filling from around 3700rpm that the advertised duration theoreticaly dictates (the upper limit of peak HP depends on the engines management and high speed mechanical durability!).
To go bigger, if not already, true solid lifters come into the picture. Although they are a pain in the butt to set up, they are vital when going high lift( also with aggressive lobe profiles with peaky ramping) and high duration. You will lose durability if having to cut back the lifter bores to account for high lift cams, what Euen has mentioned is safe when done properly, so be carefull who does that.

A point to mention,is the weakest point of the head design ( although massively improved in the 1999 head) are the restrictive exhaust ports. You will need to go larger exhaust valves and do the 3 angle cut with a nice undercut to finish along with an excellent port reshaping.

OK now, this saga above is for an out and out race engine, just to give you an idea of the complexity.
For your intended use I would go with or slightly less than what Euen has got in his trick TG sports, I would definitly do the cops conversion and go for intake trumpet length of around the 80-110mm mark.
Be sure to have chosen the correct injector sizing for your intended power output ( ask me for this calculation if you wish).

[Kieran]

its a 98 nb head
the intake runners will most likely be around 300mm long for better low rpm power not sure how big the trumpets will be as space is limited im currently tweaking a 4age silvertop quad throttle body set up the tbs are 40mm wide

what is a cops conversion and what benefit does it have

[Habanero666]

its a 98 nb head
the intake runners will most likely be around 300mm long for better low rpm power not sure how big the trumpets will be as space is limited im currently tweaking a 4age silvertop quad throttle body set up the tbs are 40mm wide

what is a cops conversion and what benefit does it have

Yes you will find the air horns to be limited in length when fabricated.

Anyway, stop guessing,unless you like going "Ghetto", this will help:
http://www.rbracing-rsr.com/runnertorquecalc.html

Coils On Plugs= cop(s) this is an excellent way to get a bigger hotter spark to ignite the fuel at the correct time! You will notice a gain in Torque right across the rev range.