A load of K series tuning questions

[jp7]

Hi all, it's getting towards the stage of gathering the bits and pieces together for my engine upgrade. At the moment i have a standard 1800 supersport running with an emerald ecu. I've managed to come by a new VHPD head/valves, seemed like a good start (Does anybody want a 1 yr old complete k16 head, email me to discuss a price) 😬. I'm probably going to use a caterham slr 4-2-1 exhaust.

I'm looking for something around the 185-200bhp, and a good spread of torque through the rev range, around the 150lbsft mark. I'm not looking purely for max bhp, but want it very drivable in the midrange. I didnt want to go to the expense and hassle of fitting forged pistons however, so i presume this will limit the revs to around 7500ish max?

Questions.

1:Jenvey or Roller barrels or some second hand KV6(original slr)? A lot has been written about rollerbarrels, is it all hype? They dont appear to be very reponsive lower in the rev range, judging by what i read on blatchat.

2:Trumpet length on induction? Is it true that the shorter they are the less torque? What length do i need?, bareing in mind i dont want to cut a hole in the bonnet!

3:Airbox or normal foam filter? Is there any benefits to an airbox, like the ones by Bernard Scouse, apart from less noise?

4:I thought about BP285 cams, obviously easier with hydraulic kind, is it worth the agro of solid lifters(i have a dry sump)

5:Do i need to port out the vhpd head further? How will it affect things if i do?

6:Are my goals 200bhp/150lbsft realistic, based on the above?

 

Well there you go, all you tuning guru's give me your thoughts.

cheers

Andy

 

[tom7]

Hi Andy,

With the only difference being your SS 1800 and dry sump, you have just described my situation.

I began with no specific output in mind but worked within certain parameters, i.e. I didn’t want to change pistons and preferred to stay with hydraulic followers.

As I wasn’t chasing every last bhp (the need to stay below 7500rpm) I have 'made-do' to a budget.

I bought a Powerspeed exhaust at £450, not the last word in exhausts but half the price of the Caterham one, with very acceptable quality and has been noise tested at 95.4db.

1. I got hold of some PTP TB’s. at a very good price, not ideal but good enough. Original TB’s can be had at a reasonable price if you look around. RB’s look great but offer no real advantage over Jenveys IMHO.

2. Can’t help with this one, I’ve got the trumpets and foam filter that came with the TB’s – should fit under the bonnet.

3. See above

4. I have BP285 hydraulic cams, a slightly gentler profile than solid types, rev characteristics suit my desire for std. Pistons and cam followers. I plan to limit myself to 7200rpm on the road which the hydraulic lifters should cope with. DVA can convert to solid lifters for added peace of mind but shimming can be a pain.

5. I have cleaned up my head a touch to match inlets because I wanted to have a go, but again, DVA does a very acceptable ‘quick port’ at a reasonable cost. It will work perfectly well without. ISTR the original SLR had no additional head work and with dubious cam timing and dodgy ECU’s managed 185bhp.

6. I have now set my goal at anything above 175bhp, Mr Oily himself suggested my spec could achieve up to 195! I’ve booked in at Emerald for early June so we will just wait and see.

Engine rebuild starts the day after Curbobugh sprint.

What ever you do, speak to DVA for the total list of possibilities.

 

Tom

 

[MikeE]

Tom,

 

Not sure if you're saying you have a 1600 or not?

 

If you do then you were in the same situation I'm now in. I have a 1600 Superlight with the addition of a Powerspeed exhaust. I need more power but on a budget

 

What exactly did you need to do/buy for your engine to get to 175bhp and what was the approximate cost (if you don't mind me asking)?

 

thanks,

Mike

[tom7]

Mike,

Mines an 1800 but that really doesn't matter. I managed to shop around and get a few good deals.

VHPD head and valve set - £450 I didn't actually buy my own, but a number of Blatchatters have sourced one from me.

PTP TB's - £350

BP285H cams and verniers - £250

Emerald - £600

Various bits and pieces, gasket sets etc up to £150

Jeez, I've never written it down like that before *eek*

You don't need a VHPD head for 175bhp, but you will need a ported one.

I havn't put it together yet, but I set 175 as an achieveable target

Hope this helps

 

Tom

[Powderpuff]

I think you should stick to the BHP you have and not get greedy 😬

 

That is until I've got the same at least

[jp7]

Hi all. Powder Puff, thats good advice from a man that has a vhpd head and a set of roller barrels under the stairs .

Tom, it'll be interesting to see what you make at emerald. As yours is pretty much what i was thinking of. However, it would appear that even the smallest of changes in spec can have a large effect, v7 slr will probalbly testify to that. I believe hes done some tuning, which on the face of it you would expect to get an increase, but ended up with a decrease in bhp. It's a funny old game.

cheers

Andy

[John Howe]

Andy if you have not read DVA's web page on tuning the K series, then please do.

 

My advice is to delay until the new year and then go all the way... rather than compromise first time around and then duplicate your work by doing it all over again a year later.

 

Dump the hydraulic followers and get wilder cams - the car is so light that you will not really notice the torque effect low down. If you are going to tune the engine, then it must be ported to enable it to breath with greater efficiency and if you are going to improve the efficiency, you will improve the power output and so you need to change to forged pistons for peace of mind.

 

IMHO

 

JH

Deliveries by Saffron, the yellow 222bhp Sausage delivery machine

[SLR No.77]

Andy - the key limiting factor is the lack of forged pistons - I'm in the same boat!

My route of upgrade is a vhpd head (£450 ex-Tom) and SLR tbs (£100 - bargain of the century) & Emerald / verniers (£675 from DVA). I have a set of vhpd cams that I came by secondhand and the original vhpd solid followers that were in my old 1400 race engine. However - I'm planning to run the supersport cams with hydraulic followers for now. I'm only prepared to go for the cam upgrade at a future date when I fit forged pistons, and quite honestly finances won't go that far yet. I'd rather knowingly rebuild the engine with forged pistons at a future date, than be forced into it when it goes pop because I was bhp greedy. Like I say, I have the cams and followers, but I'm erring on the side of caution. Needless to say vhpd head is being breathed upon anyway!

You culd probably go my route for approx £1200 + TBs + setting up. Extra £1000 for the pistons / cams / followers. I'm looking for around 175 - 180bhp, with normal rev limit.

 

Stu.

[jp7]

Reliability is the key. i see what your saying John but i think if i go over 200bhp say, its all going to get fragile. i certainly dont want to fit a steel crank/rods. So i thought by limiting the upgrade, i retain reliability. But i can make the best from what i do do. Like the trumpet lengths, they seem to have quite an effect on the overall performance.Anyway got to dash going to IAD.

cheers

Andy

[Rob Walker]

I ran for two years 187bhp out of my 1600K with the standard pistons without any problems whatsoever. I used a 7800 rev limit IIRC the engine covered 8000miles and numerous track days. A good all round cam is the 740 grind also known as BP285.

[Bare]

dunno if this relevant... but a honda RSX engine (1800cc) puts out 200 genuine Hp and will idle happily all day long... no driveability problems whatsoever... the darned things come with a 50k/5 year no questions warantee.

IF one could find one in your neighborhood this might be a clever/durable substitute... proven Reliable power.

Where I Live the Kids who own these cars are crashing them with regularity :-).. ensuring a growing supply from the wreckers... still not inexpensive, but neither is building a 'competition' engine, and then rebuilding it.

 

bare

[Jason Plato]

Well buggar me - fancy Bare bringing Honda into the thread . 😬

[CHRIS CLARK]

Hi Andy, Sorry, can't agree with John re wild cams. For good all round ease of fitting and reliability the BP285H's seem to be the answer. Mine with the ported VVC head and Piper blanking kit (basically VHPD), + PTP Tb's and Emerald ECU + Piper 285's gave 202bhp. If you want the ultimate BHP etc then solid lifters are the way to go, but for a hassle free set up then the 285's should see you OK.

 

Clamshell Club Founder Member.

[SLR No.77]

Interesting comment Rob - not sure though about the longevity of the standard piston with the increased speed and lateral forces caused by the increased stroke 🤔 That's what makes the 1600 such a sweet revving unit

 

Stu.

[tom7]

Chris,

That is a very good output. I take it yours is a K1800. As you will have seen I am building to the similar spec.

IDoes yours have forged pistons?

Did you encounter any issues with the PTP TB's?

I am also interested to know 202bhp @ rpm and what torque figure did you achieve@rpm.

Sorry for the questions but its all getting a bit exiting now.

 

Tom

[jp7]

Hi all, cheers for the responses. Does anybody know what effect an airbox has on all this. Also Steve, are you saying the 1800 pistons are more prone to failure because of the increased stroke?

Chris, It was a good bash at stoneleigh, do you think we'll make it in to LF for our ballooning!!

cheers

Andy

[SLR No.77]

Andy - who's Steve.

 

If you have a longer stroke (ie. 1800 engine as opposed to 1600) the piston travels a greater distance at a given revs. Therefore to travel the greater distance in the same time, it must accelerate faster, reach a higher top speed, and decelerate quicker before returning up or down the bore. Additionally, at half way down the bore the rod is at a greater angle to the line of travel of the piston for the bigger stroke crank, therefore the lateral force caused against the piston by the bore wall is greater. This all leads to much higher forces and more heat, then more failure. This is the basis behind the 1400 & 1600s revving much better than the 1800s.

 

Stu.

[CHRIS CLARK]

Agreed, but 1800 sorted gives better torque!

 

Andy.

I doubt we'll make L.F. as limit was exceeded, but we might make 'High Flying'!!! 😬