Stroker or Forged, which and why??

ckd281081

Member
Im in the fortunate position of having both a stroker bottom end, and also a forged one, but don't know which way to go. I've been reading about the pro's and cons of the strokers, but still cant decide which way to go. The bottom ends are as follows;

Forged one

0 miles
Mahle Pistone +1mm
Eagle rods,
ARP'd throughout
Think its ACL bearings
New oil gears

2.2 Stroker;
6000 miles
Keronite coated JE Pistone
90mm stroke H-beam con rods which have been shot peened (receipt for £1273)
half weight stroker crank
balanced assembly


The car will essentially be a road car but the odd 1/4 mile more out of curiosity than anything. The turbo i have so far is a GT3076R AR.70, fully worked head with Piper cams/gears, double valve springs etc etc. If i were to go stroker id go for a bigger turbo and aim towards 600bhp, would be limited to more like 500bhp with the forged.

In an ideal world the stroker would be the way to go, but i've read they can throw liners (this one was built by Hiteq and has had 400bhp thrown at it for 6000 miles now with no problems)(compression tested at 150-155psi on all cylinders). And i've also read multiple reports of how you they cant rev as high due to the stroke length.

Any words of wisdom that would help me decide?

Cheers

Colin
 

Empty Pockets

New Member
Most hiteq built strokers didn't have the block lined, if you have the paperwork for the build it will tell you if it's lined or not.

In which case, dropping a liner will never be a problem on that block, so much crap used to get written about strokers, to the point of people banging on about them being bad when they're talking about an engine using a standard throw crank with 90mm pistons.. Lol, clues in the name...

The only difference between the two, all being equal, is the stroker will produce more torque and earlier, and the standard stroke one will rev higher, but with reports of the hks kit with the 91mm crank frequently banging off the limiter at 9k in their d1 car i'd be happy running mine at 8-8.5k, and seeing as there's no uk cars that i know of on stock stroke and 54c head running 9k i would say the pro's of a stroker far outweigh the cons to me, lad on here had a tomie 2.2 with 91mm crank and used to rev to 8k, no problems with that as far as i know ?

Yours will have a better rod ratio with a 90mm, depending on wrist pin placement on the pistons, what crank is in yours as i can't remember the brand of any 90mm ones?
 

Empty Pockets

New Member
Just an extra thought, i remember Danny saying some kits actually used a shorter rod than standard, farndon iirc, which isn't brilliant, you want a quality, well designed kit, built well and used within it's limits will be just as reliable,

Me personally, the gtir engine looks like an excessively laggy engine which doesn't liked to be revved too much anyway, so a well designed strokers a no brainer to me,
 

red reading

Active Member
Two of us run circa 550-600hp and 470-500lbft torque on stock block and crank, I run stock conrods with a custom sort of 3076 billet, liners are hit and miss, some stroke kits run shorter rods which is a shit idea, chap in Sweden runs a primera (weaker sr20 variant ) to 9200rpm and 850hp on a stock block and crank and a gtir rocker solid lifter head and had engine failure when he had the dry sump fail......choice is yours.

there is so much to it and personally I found fitting a quality ecu with full knock control gave more benefits than anything else, with the second thing being a narrow ,equal, short length runner exhaust manifold to increase gas velocity.
 

Empty Pockets

New Member
No disagreeing the standard cranks strength, but i don't think this is a case of strength, more on ideal engine characteristics, in which every 2l graph i've seen looks laggy and doesn't rev high anyway, which to me shows the stroker having more pro's imo, i.e if you're only revving to 8k and have a decent kit being ok at 8k, you only have gains.

Shame nobody over here took a decent stroker over 500 as we would have something to compare, for a road car with decent power spread i'd go stroker, for a drag car i'd keep the standard stroke square engine, as Danny says, plenty of ways to skin a cat
 

ckd281081

Member
Thanks for the replies. Food for thought. To answer a couple of questions,, yes i have a receipt for liners being purchased and fitted. I dont know here and now (offshore at the moment) what make of crankshaft it is as the receipt just says SR20DET crankshaft, but it cost almost £2k. Heres a pic of a spec sheet that was included, and also the receipts for the conrods and shot peening ...
 
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The SR20 loves to rev, as Danny said there are plenty of guys out their rev'ing to high 8's and low 9000rpm. Its a square engine in stock form. It's the age old story of people don't do it because once apon a time a bunch of cowboy tuners that didn't know their arses from their elbows proclaimed that "if thou rev beyond 8000rpm thy rockers doth jump"

Its easy enough to change dyno settings to make an engine appear to be less laggy and there are plenty of well known tuners that do this.
 
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red reading

Active Member
The SR20 loves to rev, as Danny said there are plenty of guys out their rev'ing to high 8's and low 9000rpm. Its a square engine in stock form. It's the age old story of people don't do it because once apon a time a bunch of cowboy tuners that didn't know their arses from their elbows proclaimed that "if thou rev beyond 8000rpm thy rockers doth jump"

Its easy enough to change dyno settings to make an engine appear to be less laggy and there are plenty of well known tuners that do this.

Yep, fardon uses the shorter than stock con rods and it will be a farndon crank
 

ckd281081

Member
Educate my uneducated mind please haha,, are those rods shorter than stock even though it says 90mm and with that spec sheet? Am i wrong/stupid in thinking the standard rods are 87mm?
 

Fast Guy

Moderators
Staff member
Educate my uneducated mind please haha,, are those rods shorter than stock even though it says 90mm and with that spec sheet? Am i wrong/stupid in thinking the standard rods are 87mm?

Are you getting the stroke and rod length mixed up? Standard stroke is 86mm, strokers go 90-92mm. Rod length between centres on your diagram is 134.5
 

ckd281081

Member
yeah i probably am mate, hence why i started this post, to educate myself ;)

So going by the spec sheet for the rods, are those rods shorter? But yeah the strokes 90mm as per the receipt
 

red reading

Active Member
To gain a longer stroke the crank has to move the piston up and down further in the bore, farndon kits use stock dimension piston ( gudgeon pin to crown height) which means the conrod will need to be shorter to stop the piston from protruding from the block surface by 2mm, this means the rod is 2mm shorter than stock. We can then go into the increased rod angle at 90degree to the deck surface, extra friction from the rod angle on thrust load (piston rising and falling in the bore) and the decreased dwell and burn time at high rpm because the piston stays at top dead centre for less time every revolution, then at high rpm the piston is exceeding 25m/s which is not good for piston life.....as said its horses for courses...standard sr20 stroke is 86mm , with a stroker I think what you will gain from one area you will loose on another, I also personally prefer a bore of 86.5mm with a 87mm head gasket for a compromise of liner strength and deck surface coverage from the head gasket and use cosworth headgaskets, arp head studs are inconsistent in use and torquing down due to design so use standard ones as they are strong enough to go north of 600hp, the next question is who built the zero mile engine? Because what I know about some of the Mahle pistons in sr20 engines it may not suit your needs.
 

ckd281081

Member
I bought the forged engine form Mr Lawrence haha Stu666. chatting to him on fb right now, ill ask. Thats a fantastic post, thanks for that. One thing i would say is my pistons in the stroker engine are JE's. So, based on all of the info provided by myself,,, would you say its a good to go set up for 550ish bhp? Or stick with the forged one?
 

ckd281081

Member
Stu said to say it was a guy you know called Bob or something?? Ur mate i believe?? haha joking,, although he did say to say that. He bought it built already so doesnt know
 

red reading

Active Member
Lol, cheeky fecker, depending on what the Mahle pistons are (I.e alloy they are made of) will dictate the power they can handle, one type is more for every day cars and runs tighter clearences to stop piston slap the other is a stronger version that is more for race conditions and runs a larger Clearence , brand of pistons means not a lot tbh.....the choice is yours...who built the other engine?
 

Empty Pockets

New Member
The SR20 loves to rev, as Danny said there are plenty of guys out their rev'ing to high 8's and low 9000rpm. Its a square engine in stock form. It's the age old story of people don't do it because once apon a time a bunch of cowboy tuners that didn't know their arses from their elbows proclaimed that "if thou rev beyond 8000rpm thy rockers doth jump"

Its easy enough to change dyno settings to make an engine appear to be less laggy and there are plenty of well known tuners that do this.
Thing is, it always seems to be abroad that's doing it, never over here, all the standard mapped cars look laggy to me compared to other motors, and even the fusion mapped ones i don't think i've seen a pulsar rev past 7.5k, if everyone knows They're safe for 8.5 - 9k why's nobody doing it ? , just saying, but to me the pulsars sr20det looks laggy and never seems to be revved past 7.5k from the graphs i've seen, and yes, you can do what you want with a dyno if you're that way inclined, but i'm not talking about any car specifically, or foreign cars as i'm not there, more of a generalisation of the 10 plus standard turbo uk cars graphs compared to other jap 2ltrs.

We all know you can make anything do anything with enough money and knowledge, i'm not saying you can't get a 54c head to rev to 9k, but it's certainly not the norm, i haven't seen one uk car do it, but then i have been out the loop for ages, sure mad4it's only revved to 7-7.5k aswel, never seen dannys graph so don't know what that revs to, but as said, i've never seen one rev to 8.5-9k on paper over here ?

That's not a stroppy post btw, thought i better add this now as lately everyone seems to get the hump if you have a different opinion lol, that's just my take on it, and only on the pulsars sr20det, obviously a square config is superior if the benefits are utalised in the design, which i don't think the pulsars is, if they love to rev then capping them to 7-7.5k is obviously a negative,
 

ckd281081

Member
Brilliant replies thanks very much. I'm thinking I'm going to go with the stroker now, see what happens :/

The stroker was built by Hiteq a while ago. It's been sat for years but started 1st time after some had cranks and some plugs out/injectors off turns. Good compression across all cylinders, so bugger it, I'll go for it.

Looking at at the spec sheet I have for the rods, have they definitely been machines -2mm?
 
Thing is, it always seems to be abroad that's doing it, never over here, all the standard mapped cars look laggy to me compared to other motors, and even the fusion mapped ones i don't think i've seen a pulsar rev past 7.5k, if everyone knows They're safe for 8.5 - 9k why's nobody doing it ? , just saying, but to me the pulsars sr20det looks laggy and never seems to be revved past 7.5k from the graphs i've seen, and yes, you can do what you want with a dyno if you're that way inclined, but i'm not talking about any car specifically, or foreign cars as i'm not there, more of a generalisation of the 10 plus standard turbo uk cars graphs compared to other jap 2ltrs.

We all know you can make anything do anything with enough money and knowledge, i'm not saying you can't get a 54c head to rev to 9k, but it's certainly not the norm, i haven't seen one uk car do it, but then i have been out the loop for ages, sure mad4it's only revved to 7-7.5k aswel, never seen dannys graph so don't know what that revs to, but as said, i've never seen one rev to 8.5-9k on paper over here ?

That's not a stroppy post btw, thought i better add this now as lately everyone seems to get the hump if you have a different opinion lol, that's just my take on it, and only on the pulsars sr20det, obviously a square config is superior if the benefits are utalised in the design, which i don't think the pulsars is, if they love to rev then capping them to 7-7.5k is obviously a negative,
Russ you stroppy git, how dare you disagree with me, who do you think you are? :lol:

The point I was trying to make is that not everyone knows that the engines are safe at higher rpm due to years of misinformation, especially from dubious tuners in this country trying to sell tat like rocker stoppers. Only a few people that have had the balls to try things for themselves have found out what is possible. I guess the reason most of them are overseas is they haven't had the same level of exposure to said misinformation. Personally I don't know why Dan Fennel doesn't rev his car higher, it was the first thing I said when I saw the printouts, maybe he feels the car is fast enough as it is?

The issue the SR20 suffers from at high rpm is exhaust port flow, this causes the torque to tail off much quicker than other 2l engines. If you look at the evo heads, in stock form the exhaust flows as well as the inlet, whereas the SR is heavily biased towards inlet flow. It is possible to work around this with the right head work and turbine/exhaust sizing. Basically avoiding excess back pressure is a must. This allows the advantages of the square engine and higher revs to be realised.

As for lag it would be interesting to see a direct comparison between an SR20 and another 2L (say Evo) built to a similar spec and mapped on the same dyno with the same fuel. I have seen a few dyno' printouts from SR20's that are far from laggy; Mike Adkins GTiR made 620bhp on a relatively old school GT30/40R and spooled like a GT3071R (if Simon Norris' dyno is to be believed) and Danny's car also spools incredibly quickly for a car that in reality is close to 600bhp. As I said there are plenty of tricks that tuners use to make cars appear to spool quicker than others and fuel types make a huge amount of difference, even US pump gas will behave to UK pump fuel due to control over ethanol content.

Mine should be finished later this year and I fully intend to rev to 9000rpm (albeit on a VE head)
 
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