# Power limits of OEM 1.8T components



## kingREPTAR (Jul 27, 2012)

A list of generally accepted, safe, limits of OEM engine components, as a sort of “What to Upgrade: For Dummies.” Please help add to the list! Lets try to consolidate the “how many horsepowers on stock ___” threads.

Fuel control with standalone systems, water meth injection, etc etc will almost always allow for greater thresholds, and theres always some lucky bastard who revs to F1k on stock exhaust valves and doesn’t break a thing; this is more about the average thresholds of OEM parts while maintaining some modicum of reliability.

Im using the term “power” to describe a measure of force, be it HP, torque, or RPM.

Head
-OEM head bolts-
Recommended not to run past 400whp
OEM bolts are stretch bolts, so theyre highly apt to expand and result in head lift in high power apps.

-OEM exhaust valves-
These suck. Recommended not to rev past 7200rpm or use on a 400+chp setup, and they don’t handle high temps well at all.

-OEM intake valves
Good for 800-1000whp

-OEM Springs and retainers-
Recommended not to rev past 7200rpm.

-OEM Hydraulic lifters-
Begin to float at the mid 9k rpm range.

-OEM intake valves-
People regularly push 20Vs into the 800-1000chp range without upgrading intake valves.

-OEM Cams-
OEM cams make good power up to about 7.5k RPMs on anything comparable to a GT3071. They’re still decent after, but anything more and big cams will make a huge difference.

Block
-OEM rods-
Torque is what bends rods 
300lb/ft on a spikey, sudden onset setup, with a larger and therefor slower spooling turbo rods actually suffer less abuse.

-OEM Pistons-
Recommended replacing for over 550chp
AEB and AWD pistons have 20mm wrist pins and can handle more power.
http://forums.vwvortex.com/showthread.php?6891089-Stock-piston-power-limit


-OEM Main studs-
????

-OEM Rod bolts-
90% of rods come with ARP2000 bolts. Don’t only do rods/only do rod bolts, that is stupid.

-OEM rod and main bearings-
Recommended to replace above 8200rpm or 500whp, or any time you touch them since they’re only ~$30 more than OEM ones. 
Bearings don’t have a constant oil flow, and will occasionally be left to run on their own. Pitching your car around a bunch of corners with a non dry-sump oil pan will decrease oil flow on bearings and therefor increase wear.

-OEM flywheel bolts-
Start to chatter and loosen at ~500chp, or ~8000rpm. 
Running a viscous crank pulley will greatly alleviate the chatter of the flywheel and therefor increase the power threshold of the oem bolts.

-OEM timing equipment-
The hydraulic tensioner sucks, replace it with the IE manual kit.
The plastic impeller water pump sucks, replace it with a metal impeller pump.
The OEM belts have seen insane power levels, opinions on upgrading (aka Gates Racing) belts are highly divided.

-OEM crank pulley-
Recommended not to run past 8000rpm/500chp
After the aforementioned power levels stock crank pulleys will cause crank vibration, robbing your engine of HP and torque, and decreasing reliability. Fluidampr pulleys are expensive, but so is sending your crank through the side of your block.

Accessories
-OEM injectors-
AEB - 
AWP/AWM/AWD - 
TT225 - 

-OEM fuel rail+FPR-
???

-Mk4 Engine Mount
Good for 250 ft lbs torque, then should be replaced with a total replacement mount

-Mk4 Transmission Mount
Good for 250 ft lbs torque, then should be replaced with a total replacement or a poly insert 

-Mk4 dogbone
Dogbone good for ridiculous horsepower. Insert good for 250 ft lbs torque

-02j axles on mk4
Good for 300 ft lbs torque. This number goes down as your axle angle increases due to lowering your car. If you can keep suspension geometry correct via drop spindles or otherwise, the 300 ft lbs number stays true.

-02m axles on mk4


-MK4 stock 2.25" exhaust
The choke points on this are the resonator and the cat. Launch control should not be used on the stock exhaust. The stock muffler is known to blow up when you utilize launch control

-06a or 058 crank gear
This is good for 400whp+. However, when high RPM's are regularly involved (7500+) it would be smart to dowel pin this gear or replace it with a steel crank gear

-02m shift forks

-02m slave cylinder


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## Vegeta Gti (Feb 13, 2003)

This list need a lot of correcting

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## kingREPTAR (Jul 27, 2012)

lol, dammit Cris. Then chime in with the correct **** homie!


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## jstnGTI (Jan 30, 2012)

Awesome idea. Faq worthy - with correct, unbiased, proven, accurate data.


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## Vegeta Gti (Feb 13, 2003)

Def Lathan. This is a great idea. When I get home I'll go on the laptop. There is Def others who can help. 

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## Dave926 (Mar 30, 2005)

I always thought rods and exhaust valves you were fine for ~ 450whp.

Its the other hardware that just helps you get there easier.

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## ejg3855 (Sep 23, 2004)

*FV-QR*

Rods are good for 300-320tq max with the spikey onset of boost. More torque without a big spike. Def setup dependent.

People have made 600+ on stock head bolts, its just not as common. 

Rod/Main Bearings are a non-issue. Sure Calicos are nice if you are trying to squeeze every last ounce of HP but not needed.


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## kingREPTAR (Jul 27, 2012)

:beer:
Thanks for the input everyone.


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## rstolz (Jun 16, 2009)

> TT225 -


2 varieties of the TT225: 
AMU - ('01-'03)
narrowband 
20mm wrist pin
[email protected] injectors
non-VVT

BEA - ('03-'05)
Wideband 
19mm wrist pin
[email protected] injectors
VVT

beyond that, they're pretty much the same, ME7, DBW, blah blah blah.


I know that's not really on point for the thread, but too often the TT225 is considered a single engine, when there were 2 distinctly different versions, and knowing the differences will tell you what upgrades to make, and when.


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## ejg3855 (Sep 23, 2004)

*FV-QR*

I am pretty sure the TT225 block has more reinforcement, appears to have forged main caps or atleast mine does.


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## rstolz (Jun 16, 2009)

> I am pretty sure the TT225 block has more reinforcement, appears to have forged main caps or atleast mine does.


true. I was trying to limit my post to just those items that differentiate the AMU from the BEA; the cross-webbed block and forged main caps are common between them.


At some point though, in upgrading your car, you will need to know the specifics of your engine code, since each code has its differences that are good for different power levels. A lot of us know that, but many more need to be reminded.


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## Doooglasss (Aug 28, 2009)

I made a stock piston power limit thread if you want to add that in: 

http://forums.vwvortex.com/showthread.php?6891089-Stock-piston-power-limit

Seems like the general vote was around 500chp


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## Mike Pauciullo (Jan 8, 2009)

stock intake valves are good for 800-1000whp


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## Vegeta Gti (Feb 13, 2003)

Yup. Exhaust valves no likey 400+.

Stock pistons have seen over 600whp.. Would Def recommend replacement if literally posing 550 or higher crank

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## Mike Pauciullo (Jan 8, 2009)

One of my spare engines just has rods in it lol


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## Vegeta Gti (Feb 13, 2003)

As Mike said.. I've been rods only 450whp+ for 6 years...

Mike is making waaayyyyyy fun more lol

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## brwmogazos (Oct 12, 2011)

Do we have any more examples concerning the head bolts?

OEM vs ARP?

I thought 500 HP @ the crank would be OK for the OEM bolts...


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## Vegeta Gti (Feb 13, 2003)

The OEM actually aren't that bad. They can handle 400whp 

My personal preference are ARP bolts

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## Zowexx (Sep 23, 2013)

Vegeta Gti said:


> Yup. Exhaust valves no likey 400+.
> 
> Stock pistons have seen over 600whp.. Would Def recommend replacement if literally posing 550 or higher crank
> 
> Sent from my SPH-L720 using Tapatalk


so not more than 400 chp with stock exhaust valves ?


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## l88m22vette (Mar 2, 2006)

Vegeta Gti said:


> My personal preference are ARP bolts


And there are specific ones for smallport/bigport heads, and using an AEB on an 06A block, correct?

Edited because I hadn't had my coffee yet


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## rstolz (Jun 16, 2009)

> l88m22vette
> Quote Originally Posted by rstolz View Post
> 2 varieties of the TT225:
> AMU - ('01-'03)
> ...


They both use 20mm pins. We were both wrong. Looks like this pissing match ended in a tie.


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## hermes350GT (Oct 18, 2013)

The amu 225's have dual side intercoolers....


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## groggory (Apr 21, 2003)

OP, Please keep your initial post updated with all the additional information that is thrown your way. That way future FAQ followers can reference your initial post as the golden post

I'd like to also include some powertrain bits in this too for the platforms that come stock with 1.8t's (not swaps).

* Mk4 Engine Mount
Good for 250 ft lbs torque, then should be replaced with a total replacement mount

* Mk4 Transmission Mount
Good for 250 ft lbs torque, then should be replaced with a total replacement or a poly insert 

* Mk4 dogbone
Dogbone good for ridiculous horsepower. Insert good for 250 ft lbs torque

* 02j axles on mk4
Good for 300 ft lbs torque. This number goes down as your axle angle increases due to lowering your car. If you can keep suspension geometry correct via drop spindles or otherwise, the 300 ft lbs number stays true.

* 02m axles on mk4
<need info>

* mk4 stock 2.25" exhaust
The choke points on this are the resonator and the cat. Launch control should not be used on the stock exhaust. The stock muffler is known to blow up when you utilize launch control

* 06a or 058 crank gear
This is good for 400whp+. However, when high RPM's are regularly involved (7500+) it would be smart to dowel pin this gear or replace it with a steel crank gear

* 02m shift forks

* 02m slave cylinder


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## groggory (Apr 21, 2003)

FAQ'd


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## kingREPTAR (Jul 27, 2012)

Edited to reflect new info. :beer:


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## Pat @ Pitt Soundworks (Nov 14, 2008)

> -02j axles on mk4
> Good for 300 ft lbs torque. This number goes down as your axle angle increases due to lowering your car. If you can keep suspension geometry correct via drop spindles or otherwise, the 300 ft lbs number stays true.


drop spindles don't change axle geometry, they correct control arm geometry. You need motor mount spacers to raise the engine to _help_ correct this.


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## Zowexx (Sep 23, 2013)

*exhaust valves*

I read that the exhaust valves dont handle heat well at all... ehm .. will they hold for 550 bhp?


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## kingREPTAR (Jul 27, 2012)

See original post. 400chp, and 7200rpm. If you plan on making 550bhp, you should really upgrade exhaust valves, springs, retainers, head bolts, & rods


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## Zowexx (Sep 23, 2013)

kingREPTAR said:


> See original post. 400chp, and 7200rpm. If you plan on making 550bhp, you should really upgrade exhaust valves, springs, retainers, head bolts, & rods


I´ve built the engine with je pistons 8:5:1 compression 1st OD, h beam IE rods, acl Racing bearings, heavely ported small port AJQ head stock intake and exhaust valves, supertech valve springs with titanium retainers but colonel valves are expensive as ****!


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## kingREPTAR (Jul 27, 2012)

Supertech non-inconel valves should are fine


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## Vegeta Gti (Feb 13, 2003)

I prefer stainless over inconel.

Bend over break and I shouldn't have such a ****ty tune or be in wot so long as to have then fail from heat.


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## SpOoOling1.8T (Dec 12, 2004)

Any input in fueling? I would like to know about fuel rail limit, fuel line from tank to up front? etc


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## Pat @ Pitt Soundworks (Nov 14, 2008)

The fuel rail has 5/16 lines. With enough fuel pressure, you can reach 600hp. The body of the rail has the same internal area as 10an hose, so if you cut the 5/16 lines off and weld an an fitting to the rail, you can support a lot more power.


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## silvercar (Aug 23, 2004)

I have to disagree with a lot of what is in this thread. Most specifically the pistons. With correct tuning 90-95% of the guys on this forum will not exceed the limitations of stock slugs. Choosing to upgrade is one thing, but to try to sell the idea that your pistons will explode at 500 horsepower is absolutely laughable. The list of guys who have done more, and reliably at that, is long, and states otherwise. I'm not trying to be an ass, but I really think some people are wasting money on hardware they don't need. :beer:


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## Vegeta Gti (Feb 13, 2003)

Instead of saying its true or Gause. List the implications, i usually do.

I'm 486. Stock awp pistons.


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## silvercar (Aug 23, 2004)

Vegeta Gti said:


> Instead of saying its true or Gause. List the implications, i usually do.
> 
> I'm 486. Stock awp pistons.


I was trying to avoid saying "I this," or "I that." The OP wanted to leave off statistical outliers. But- I'm running a 35r at 25ish psi on stock AEB pistons. So, however much that is. But like I said, you could dig up a laundry list of people on this forum who have done the same type thing.


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## Vegeta Gti (Feb 13, 2003)

Still beter to put a slightly lower limit because 99% of people don't know better. 

That's called dealing with the masses. You and i did it. 5 others won't.


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## silvercar (Aug 23, 2004)

Vegeta Gti said:


> Still beter to put a slightly lower limit because 99% of people don't know better.
> 
> That's called dealing with the masses. You and i did it. 5 others won't.


I mean, I get that I guess. But what I'm saying is that with responsible tuning and the correct supporting hardware, that all 7 of us can do it. Am I that far off the status quo?


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## Vegeta Gti (Feb 13, 2003)

unfortunately you are brother.


it's all about cheap here mostly.


chose 3....

fast
cheap
reliable


most people want fast for cheap. never works out. it's the absolutel truth with the mass majority today in the VW crowd....****..in humanity, especially the USA


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## Vegeta Gti (Feb 13, 2003)

Sorry . Choose 2


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## iamdagerman (Feb 19, 2006)

How much can the cast crank handle?


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## Miguel_s# (Mar 28, 2014)

very good topic


so exhaust valve are good above 400hp and they dont like high temp

what is the maximum temperature the exhauste valve can handle?


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## mattryan1.8t (Mar 12, 2011)

Awesome post, I'd love to know clutch and injector thresholds :beer:


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## nater1107 (Jan 27, 2014)

I'd like to see the stock clutch limit also


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## KmosK04 (Dec 18, 2012)

nater1107 said:


> I'd like to see the stock clutch limit also


410nm-430nm


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## Gulfstream (Jul 28, 2010)

iamdagerman said:


> How much can the cast crank handle?


Don't get a cast crank.


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## Alec's TT (Jan 28, 2013)

Trying to find the recomended limit of main caps before going billet


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## Mike Pauciullo (Jan 8, 2009)

Alec's TT said:


> Trying to find the recomended limit of main caps before going billet


I been going mid to low 9's on factory mains and no girdle for a few years now.


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## Audifan7868 (Apr 17, 2016)

rstolz said:


> 2 varieties of the TT225:
> AMU - ('01-'03)
> narrowband
> 20mm wrist pin
> ...


The bea has 20mm also

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## Audifan7868 (Apr 17, 2016)

hermes350GT said:


> The amu 225's have dual side intercoolers....


So does bea

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## sakispolo (Oct 6, 2015)

What about main cap bolts? How many whp can they handle? I read that they are stretch bolts and need to be replaced every time they are removed. Not that I would ever try to use them again( they cost nothing) but has anyone here used the same after removal? Also head studs, just out of curiosity.

Thanks


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## rbd2 (Jan 23, 2017)

What are the limits of the stock fuel lines on the mk4 jetta/golf 1.8t?


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## Vegeta Gti (Feb 13, 2003)

I would say, personally, 550-600whp is where you can see it causing issues and being restrictive. 

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