How much boost/ power can I expect to run,

16th January 2013, 16:06

Hi all, How much boost/ power can I expect to run on my engine without changing the rods,

Here is the spec of my engine:
C2 VTS JP4 Engine
JE forged low comp pistons
Ballanced crank, rods and pistons
420cc injectors
KMS map sensor
fully rebuilt with all new bearings, seals and gaskets

Cheers

16th January 2013, 16:11

Quote:

Originally Posted by Rhysupply

Hi all, How much boost/ power can I expect to run on my engine without changing the rods,

Here is the spec of my engine:
C2 VTS JP4 Engine
JE forged low comp pistons
Ballanced crank, rods and pistons
420cc injectors
KMS map sensor
fully rebuilt with all new bearings, seals and gaskets

Cheers

I'm sure it will take 20 bar at least, for a few milliseconds.

on a serious note i wouldn't run any boost on standard rods really.

16th January 2013, 16:39

Completely depends on how good the mapping is and how low the compression is, but with good mapping about 300bhp

16th January 2013, 16:51

I wouldn't know how low compression it was it was built by high flow heads, so you think it's prob just worth changing them,I want to see about 250+ bhp

16th January 2013, 16:58

You've missed out the turbo.. Without that's it's pretty hard to give you an accurate answer.
My friend has been running 250@wheels now for a couple of years now. ARP rod bolts also. He will be changing them shortly as fatigue will well and truly have set in by now

16th January 2013, 17:36

Gt25, you think those figures are achievable ?

16th January 2013, 17:52

Yes you should reach that without too much trouble, as long as the exhaust bore is big enough and you run 2" boost piping

And for the rods you should be ok as the boost increase with a gt25 isn't that vicious..... the rods are actually stronger than a lot of people think and cast iron rods in some cases are actually stronger than some of the cheaper steel rods on the market

Edit: I meant you'll reach 250 @ the fly, not the wheels lol

16th January 2013, 17:56

Not witha gt25 I'm afraid. My friend is using a gt28rs..
At 1bar of boost expect approx 210@wheels with gt25

16th January 2013, 22:45

So what's 250 at the fly like 220 at the wheels? Cheers for the comments btw

17th January 2013, 09:10

Quote:

Originally Posted by Jordysport

I'm sure it will take 20 bar at least, for a few milliseconds.

on a serious note i wouldn't run any boost on standard rods really.

With ARP bolts, standard rods are comfortable for 250atw.

17th January 2013, 10:28

we have seen some standard rods (when used with arp bolts) run in excess of 350bhp

but then we have seen others running less than 300bhp bend the tops of the rods =0/

i ran over 300bhp on standard rods on my own car for 2 years, then we went to just over 400bhp before a stock rod bolt let go.

doesnt really seem to be much consistency. luck of the drawer id say!

generally we say up to 250bhp - stock rods ok. take your chances up to 300.
if you intend to go to 300+ then forge it.

hope that helps

- colin

17th January 2013, 11:03

Quote:

Originally Posted by Ross

With ARP bolts, standard rods are comfortable for 250atw.

I would doubt that if this is a c2 vts jp4 engine
rods are thinner and not fully floating little ends-dif rods+ pistons than a saxo /106 engine

I am suprosed if je do a piston that is meant to fit these rods ,as it is a heat up the rods to fit pistons and no circlips

17th January 2013, 11:07

Quote:

Originally Posted by Ross

With ARP bolts, standard rods are comfortable for 250atw.

The Spec the OP listed doesn't have ARP bolts.

Plus when you spend so much on a rebuild of the bottom end and then spend a lot on the head, then a rebuilt turbo, and you can't be bothered to spend a measly £500 odd for forged rods. when a rod failure could destroy all of the above which you spent way more than £500 on.

As Colin said Take your chances but i wouldn't, and I'd always advise the same with rods.

I've been there done that and got the tshirt, its not worth the risk. also question to yourself; you've rebuilt your engine pretty much ground up with new/uprated components, you are running standard rods. and as colin has said they are unpredictable and don't go at a specific power output, what are you going to be thinking when going flat out in the car.

Quote:

Originally Posted by atspeedracing

we have seen some standard rods (when used with arp bolts) run in excess of 350bhp

but then we have seen others running less than 300bhp bend the tops of the rods =0/

i ran over 300bhp on standard rods on my own car for 2 years, then we went to just over 400bhp before a stock rod bolt let go.

doesnt really seem to be much consistency. luck of the drawer id say!

generally we say up to 250bhp - stock rods ok. take your chances up to 300.
if you intend to go to 300+ then forge it.

hope that helps

- colin

17th January 2013, 11:18

Quote:

Originally Posted by Jordysport

The Spec the OP listed doesn't have ARP bolts.

Plus when you spend so much on a rebuild of the bottom end and then spend a lot on the head, then a rebuilt turbo, and you can't be bothered to spend a measly £500 odd for forged rods. when a rod failure could destroy all of the above which you spent way more than £500 on.

As Colin said Take your chances but i wouldn't, and I'd always advise the same with rods.

I've been there done that and got the tshirt, its not worth the risk. also question to yourself; you've rebuilt your engine pretty much ground up with new/uprated components, you are running standard rods. and as colin has said they are unpredictable and don't go at a specific power output, what are you going to be thinking when going flat out in the car.

I'm not sure what point you're making tbh.

I've run over 300hp on standard (JP4) rods. I now run forged rods but I'm way beyond 300hp so it's a no-brainer.

I believe he'll be "ok" up to 250hp on standard rods. I implied that he should change the rod bolts as these (generally) let go first.

17th January 2013, 11:29

Quote:

Originally Posted by Ross

I'm not sure what point you're making tbh.

I've run over 300hp on standard (JP4) rods. I now run forged rods but I'm way beyond 300hp so it's a no-brainer.

I believe he'll be "ok" up to 250hp on standard rods. I implied that he should change the rod bolts as these (generally) let go first.

Ok I'll Try again!

- Colin has said that the Rods (i assume with arp bolts) can go at a large range of power bands

- you spend £3,000 on your bottom end & Rebuild
- you spend £1,500 on your turbo system
- you spend £1,500 on your head (cheap head work)

- The only thing that's not uprated in the bottom end is the rods, which are the weak point in most engines when high tuning.

- I wouldn't be happy knowing that the rods can let go at an unknown value of power, why risk all that investment when a rod failure could destroy all the work you have done. £6,000 of engine or £500 odd of Forged Rods I know what i would choose.

- Imo knowing this I would be seriously conservative on the engine and whats the point if your nervous all the time on the throttle knowing the rods could go at any power, might aswell have 100+bhp less and be able to use it all.

Its the OP's choice but I wouldn't be seen dead using standard rods on that sort of engine.

17th January 2013, 11:34

I've run over 300hp on standard (JP4) rods. I now run forged rods but I'm way beyond 300hp so it's a no-brainer.

jp4 rods are not same as saxo --
pistons are shrink fit on jp4 rods,same as a vtr --but jp4 ones are thinner around the top of the little end bush +narrower --are you saying you have run 300 bhp on these rods or std saxo fully floating rods
saxo is a j4 engine
and no i would not council running anything more than 220-230@wheels on std rods.
as for fitting arp bolts to std rods --waste of money --£100 for bolts and you can have rods +bolts @£380
If you are running std ish rpms then std bolts take no more strain than noraml --its higher rpms tha strecth the bolts --work it out the extra load at std rpms is all down wards as its a bigger bang --piston load is no more coming up the way at std rpms

17th January 2013, 12:13

Quote:

Originally Posted by axsaxoman

are you saying you have run 300 bhp on these rods or std saxo fully floating rods

I've run (two years ago) 300hp on standard jp4 rods - yes. As I say, I now run forged for obvious reasons.

We're arguing about something different to the OP's original question however. It's not "should I run forged or not" it was "how much power can I (get away with) run on standard JP4 rods". I said 250hp, you say 230hp, Colin says 250hp. So we're all in the same ballpark.

Yes - he SHOULD run forged. But that wasn't the question.

17th January 2013, 12:42

we are not arguing --I,m just suprised to hear you say you used shrink fit con rods on forged pistons which have circlips to retain the piston pins ,
as there is no little end bush in the std jp4 rods --the pin does not turn in the rod , so i am guessing you did not fit the circlips as they were not needed
j4 rods have a little end bush
jp4 do not and are shrink fit
what i am queriing is if they were jp4 rods and not j4 rods ,as in saxo engine

17th January 2013, 12:47

If hi flow heads built it, Id suggest ringing them and speak to Andy.

Hes a very friendly chap and will know more about his own build, and could probably advise you as he will know the spec in more detail.

Here is his number incase you cant be bothered to google 01620 880763

17th January 2013, 13:42

Quote:

Originally Posted by axsaxoman

we are not arguing --I,m just suprised to hear you say you used shrink fit con rods on forged pistons which have circlips to retain the piston pins ,
as there is no little end bush in the std jp4 rods --the pin does not turn in the rod , so i am guessing you did not fit the circlips as they were not needed
j4 rods have a little end bush
jp4 do not and are shrink fit
what i am queriing is if they were jp4 rods and not j4 rods ,as in saxo engine

They were 100% JP4 rods yep - the whole engine was JP4, just with forged pistons. Atspeed fitted them - I'm afraid I don't know how (ref: circlips etc).

17th January 2013, 15:48

£380 For Rods & Bolts thats a bloody bargain. Its a no brainer for me,

17th January 2013, 21:41

Is this an engine that sold on ebay for like £350 or something like that? I remember one being sold with the exact spec.

If it is the engine i'm thinking of, I think it was run a couple of thousand miles with a supercharger already.

It may be worth investing some money to get some proper rods and a rebuild just to give you piece of mind that you have done as much as you can for reliability -Then run what you like!

17th January 2013, 23:17

Quote:

Originally Posted by Jordysport

£380 For Rods & Bolts thats a bloody bargain. Its a no brainer for me,

And I can get people probably the same rods/arp's for 260quid posted...

18th January 2013, 07:48

Quote:

Originally Posted by Steph_at_constella

If hi flow heads built it, Id suggest ringing them and speak to Andy.

Hes a very friendly chap and will know more about his own build, and could probably advise you as he will know the spec in more detail.

Here is his number incase you cant be bothered to google 01620 880763

Because the engine wasn't mine when they bought it they can't tell me anything about it :/ customer confidentiality.

18th January 2013, 07:51

Thanks guys for all the posts made a very interesting read,so basically it's luck of the draw at anything over 250,I did forget to put that it does have arp bolts,I think I'm going to hold fire for a bit and get a set of decent rods because I think I'd cry if they went.

18th January 2013, 19:38

Quote:

Originally Posted by gazza808

And I can get people probably the same rods/arp's for 260quid posted...

How so ?

18th January 2013, 19:39

Quote:

Originally Posted by martyno

Is this an engine that sold on ebay for like £350 or something like that? I remember one being sold with the exact spec.

If it is the engine i'm thinking of, I think it was run a couple of thousand miles with a supercharger already.

It may be worth investing some money to get some proper rods and a rebuild just to give you piece of mind that you have done as much as you can for reliability -Then run what you like!

Yeah I bought it off a guy called martin was emigrating to Australia so needed to get rid, he said was run with supercharger for a bit.i wouldn't mind knowing a bit more history on it.

18th January 2013, 20:08

Quote:

Originally Posted by Rhysupply

How so ?

By cutting out the British middle man putting his bit on,
If your interested ill get you his contact details.

19th January 2013, 10:50

Quote:

Originally Posted by gazza808

By cutting out the British middle man putting his bit on,
If your interested ill get you his contact details.

Yeah I wouldn't mind, what make are they.

19th January 2013, 13:15

I unbranded, as are 90percent on the rods when they arrive in England, they are the same rods pec sell just with out pec on them,
I'll pm you details when he gets back to me.