Long Term Review: Hybrid Users Post Here

[Maxwell Power]

Originally Posted by PSolbergfan

That is unbelievable that you blew a ring land. Are you certain of this? I would say that, that's a pretty safe power level for a stock STi block. Even with stock pistons.

using a turbo like a tdo4 only makes the reliability issues worse.

I know it's hard to believe, but you were just looking at power levels. Power levels don't dictate reliability in this configuration. The tendency of an engine to knock does. A hybrid with a tdo4 is more likely to knock than a hybrid with a vf39. It comes down to the very restrictive turbine housing found on the tdo4. A restrictive turbine housing will limit the amount of scavenging that occurs during valve overlap. In extreme cases it will actually result in polluting the cylinder with exhaust gas instead of clearing it out with a fresh air/fuel charge. If you can't remove any heat during overlap you are going to increase the tendency of the engine to detonate.


Tdo4 turbos do not belong on 2.5L engines at all and they are even worse on hybrids with stock heads.

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[Ryan314]

Interesting... but why don't you hear issues from 06-08 WRX owners with a 2.5L and the TD04?

[Maxwell Power]

two things:
1. You do. Lots of WRX's break pistons, but not as many as STi's. One reason is that they aren't tuned as aggressive because owners are worrying about their transmissions. I have customers tell me on many occasions to keep the torque under control because they don't want to blow their trans.
2. It's not as bad because of the larger chamber footprint for the reasons that I have already explained.

[sube-trex]

Originally Posted by Maxwell Power

current status?

I think the current status is important for everyone's post.

IMHO that is based off many of these engines, a Hybrid without proper chamber work (regardless of who tuned it) is a ticking time bomb. Many people talk about how great the extra quench is, but I think it has a very very negative effect as it places a lot of material in the way of the escaping exhaust gases creating large hot spots.

All the more reason to get the proper machining done. I have been looking at this from an aviation standpoint and have decided to do the machining other than not getting it done. I had a local tuner talk about how great the hybrid setup is.

Originally Posted by Maxwell Power

here is what I'm trying to explain in a really crappy MS Paint drawn picture.Point A is the large quench pad that is created by placing a 2.5L bore on a 2L head. Point A on the non enlarged head has a greater quantity of exhaust gas passing that point in addition to a relatively stagnant pocket (B) just below it. When the piston moves to the top, that pocket is cleared out and the hot
gasses are pushed up and around the corner at Point A. This causes the heat to be deposited into the head at that point which creates a hot spot that will cause detonation the next time the cylinder is filled and compressed. Also, filling that void around the corner takes more
time and energy which can rob power. Someone might argue that the cool charge coming into the cylinder the next time around will cool off that hot spot. That is what I believe happens to a degree under light loads and when the intercooler is cooling the intake charge off
significantly. Under high boost and heat soak conditions the spot will not be cooled sufficiently by the intake charge and that point will only get hotter and hotter.

In the cylinder on the left, the point A only has
a small amount of gases flowing past it and the very small pocket (B) doesn't retain a lot of heat or stagnant gasses.

This is why Hybrids are so unreliable. You can have a 9:1 compression hybrid with a larger chamber and it would be leagues above a 9:1 compression hybrid with no chamber work in both power and reliability.

I like how you cut through the info of the over-glorrified hybrid setup. Almost all shops I've talked to have mentioned only geting the machining done if you want to have 400plus whp and don't mention anything about the reliability of the hybrid.

Originally Posted by Maxwell Power

using a turbo like a tdo4 only makes the reliability issues worse.

I know it's hard to believe, but you were just looking at power levels. Power levels don't
dictate reliability in this configuration. The tendency of an engine to knock does. A hybrid with a tdo4 is more likely to knock than a hybrid with a vf39. It comes down to the very restrictive turbine housing found on the tdo4. A restrictive turbine housing will limit the amount of scavenging that occurs during valve overlap. In extreme cases it will actually result in polluting the cylinder with exhaust gas instead
of clearing it out with a fresh air/fuel charge. If you can't remove any heat during overlap you are going to increase the tendency of the engine to detonate.
Tdo4 turbos do not belong on 2.5L engines at all and they are even worse on hybrids with stock heads.

Yes,even more parts to buy to go over my budget!! But at least I will be making safe power.

[sube-trex]

Could these blown ring lands be a result of the increased quench and gas temp?

[carbonrex1]

axis stage 2 block(2.5l)
stock wrx heads, stock valve train and cams
cometic head gasket
vf-22
80,000 hard miles/6 years
300hp and 320ftlbs

currently down with a burnt valve, the heads have around 160k miles.

[Ryan314]

^Whats transmission?

[carbonrex1]

sti ra with stock 5th.

[rainwrx]

Mileage since installed: 26,000
Type Engine and Internals: Raw Performance "Street Series" Short Block -- Stock ej257 with CP Pistons
Valve-train: Stock 2.0L heads, Crower Stage 2 264/264 cams, Springs, Retainers
Head Gasket Choice: Stock STi
Tune: Tuned with no problems -- less timing than STi
----- 340whp/340wtq (TD05 18G, 8cm2 hot side, 20psi)

Current status: Runs great and strong. A little piston slap when cold -- goes away when warmed up.

Will consume about 1.5 quarts of oil per 1500 miles when run hard (lots of 7000rpm and engine braking, downshifting), also on long, fast highway trips. Normal around town driving uses about 1 quart per 3,000 miles.

Planning to install Blouch Dom 3 for 400whp. For future rebuild I will consider having the chambers done to match 2.5 heads' CC, and PnP.

[pokybear]

My son and I are about to embark on a hybrid project, but before I start buying parts I thought I'd see if any hybrid builders out there want to comment on our plans? Your thoughts would be greatly appreciated. I'm particularly unsure of the cams, turbo, and injectors. Please be kind to this newbie. This is my first build since I was a kid, and back then it was muscle cars and California bugs.

Platform 2002 WRX 190K miles
Short Block EJ257
Oil Pump 2008 USDM STi 11mm
Heads Original EJ205
Heads Port and Polished
Valves Original
Valve Springs Original
Head Gasket Cosworth RCH-2145 Head Gasket Set EJ25 (1.5mm)
Head Studs OEM
Cams Brian Crower Stage 2 272/272
Injectors Original
Turbo IHI VF39
Exhaust Original
Transmission Later model OEM
Timing Belt Gates Racing Kevlar Timing Belt
Clutch Rebuilt at 157,018 miles

[notraceready]

Miles since install: 12,000
Type Engine and Internals: Raw Performance "Street Series" Short Block -- Stock ej257with CP Pistons
Valve-train: Stock 2.0L heads
Head Gasket Choice: Cometic head gasket
Tune: Jorge at p and l motorsports. 366/380 whp and torque.

Current status: running well. Pulls hard

[polskaboys]

Originally Posted by pokybear

My son and I are about to embark on a hybrid project, but before I start buying parts I thought I'd see if any hybrid builders out there want to comment on our plans? Your thoughts would be greatly appreciated. I'm particularly unsure of the cams, turbo, and injectors. Please be kind to this newbie. This is my first build since I was a kid, and back then it was muscle cars and California bugs.

Platform 2002 WRX 190K miles
Short Block EJ257
Oil Pump 2008 USDM STi 11mm
Heads Original EJ205
Heads Port and Polished
Valves Original
Valve Springs Original
Head Gasket Cosworth RCH-2145 Head Gasket Set EJ25 (1.5mm)
Head Studs OEM
Cams Brian Crower Stage 2 272/272
Injectors Original
Turbo IHI VF39
Exhaust Original
Transmission Later model OEM
Timing Belt Gates Racing Kevlar Timing Belt
Clutch Rebuilt at 157,018 miles

PMed YOU

[paintbing]

Originally Posted by pokybear

My son and I are about to embark on a hybrid project, but before I start buying parts I thought I'd see if any hybrid builders out there want to comment on our plans? Your thoughts would be greatly appreciated. I'm particularly unsure of the cams, turbo, and injectors. Please be kind to this newbie. This is my first build since I was a kid, and back then it was muscle cars and California bugs.

Platform 2002 WRX 190K miles
Short Block EJ257
Oil Pump 2008 USDM STi 11mm
Heads Original EJ205
Heads Port and Polished
Valves Original
Valve Springs Original
Head Gasket Cosworth RCH-2145 Head Gasket Set EJ25 (1.5mm)
Head Studs OEM
Cams Brian Crower Stage 2 272/272
Injectors Original
Turbo IHI VF39
Exhaust Original
Transmission Later model OEM
Timing Belt Gates Racing Kevlar Timing Belt
Clutch Rebuilt at 157,018 miles

I would change it a bit... I don't want to get into an debate as there are plenty of other threads, but here's what I'd change -
- APR head studs instead of OEM (this is a no-brainer)
- OEM STI head gaskets instead of Cosworth 1.5mm (Due to HORRIBLE QUENCH This is the wrong way to lower compression)
- P&P Heads WITH Chamber shaping to properly reduce compression (check into Equilibrium Tuning services)
- Upgrade exhaust to 3 inch turboback
- Injectors - VF34 required the Pinks and even then with pinks and the 2.5 block, I was maxing mine out. You stand NO chance with stock 440's - MUST UPGRADE. Minimum pinks or 650's.
- Upgrade valves if you are going with those cams... The cams you chose are shifting the powerband to the right, which = Higher RPM/more redline driving - you need better springs to ensure the valves don't start to float as the springs fatigue.
- By all means a better turbo. If you are doing ALL the work above and keeping a lousy STI turbo, you're doing it wrong. I've got a fp green and it spools fairly quick - not as fast as the VF34 and 39, but more power all around.

Notes - If you don't want to shape the heads, at a minimum use low-compression pistons and deshroud the valves. Your quench is all screwed up when using a thicker headgasket and OEM pistons. Remember the guys running the Cosworth headgaskets are also running custom pistons that fix the quench issue. Just because it's coming from a reputable company, doesn't mean it's going to work with your setup.

My $0.02

[Ryan314]

^Good info. To add to the piston recommendation, JE makes a hybrid specific piston for users that do not have their heads CC machined. I almost was gonna go down this route, but decided to just send my heads to EQ and go with standard OEM compression forged Mahle pistons. I felt like this is the more reliable route.

[sube-trex]

A note on the JE-pistons.

I was going to go this route but, for the price of the pistons+install was just +/- 200 difference all together, but that's +/- 200 for getting the heads machined by EQ. In the end I see it as insurance.

What's not good is you have people going to their local shops and asking these same questions. For example before I knew about EQ's service: the shop here boasted being the first one to do a hybrid swap and been running strong for +5 years making it sound golden. Saying that its not necessary to do the machining unless you want to get to 400 hp; his statement really didn't make sense to me and I became real suspicious. This shop is the only shop around my area (Perrin Headquarters, PDX tuning, COBB Surgeline, Maxwell Power [Dom]) that is touting about not getting any head-work done until you reach xxx - hp

[pokybear]

Thanks to everyone who has shared their thoughts. All great information. Given I don't have an unlimited budget, which of these modifications would you put at the top of the list, or conversely, which would you put at the bottom? Our goal is to build a reliable daily driver that makes 300 to 350 WHP. Thanks again, I'm learning loads!

[sube-trex]

^
Check out Unabombers Faqs, also the stickys in the Engine Build thread. It will give you even more info.

It all boils down to the tune, you can have a $10K engine and have it blow on you at 5K miles because the tune was to hell. That's ur first priorit is to find a reputable tunner.

Dom from Maxwell Power for instance : he once tuned a vehicle in shop and it started developing a problem with the rear diff. He went above and beyond to diagnose the problem, he took the rear diff from HIS personal car and installed it onto the customers' just to narrow it down. After this the cuatomer was able to get it fixed under warranty.

*sorry about the grammer ,im tying on my small palm pre.

[Maxwell Power]

thanks for the kind words sube-trex.

My opinion based on what I have seen with all the motors we build and from what I have observed on other motors:

Hybrid:
If you're going to do the hybrid, the chamber work is so crucial regardless of power output. I would honestly say, do the headwork OVER a forged piston if your power goal is only 300-350whp.

Here's why: The OEM pistons are known for their cracking when pushed hard or when poorly tuned. However, with a proper tune the engine is very reliable ( Especially if the IAT sensor is moved post intercooler) and very quiet. In a knock free environment the OEM piston and it's tighter piston to wall clearances will give you all the power you desire and the reliability of a stock engine. You will have no piston slap and therefor no worries associated with it. You will be able to drive the car sooner after starting and not have to worry about excessive piston scuffing during warm up. You will have low levels of blowby with the tighter ring gaps and tighter clearances. This creates a cleaner intake tract, cleaner cylinders that are less prone to knock because of less oil vapor carried into the engine. Your oil will last longer too. The new 09 STi shortblocks have a new bearing material that is stronger than previous years as well as ideal rod bearing clearances (a big plus from older STi blocks). The oem rod bearings now come from the factory at .0018". This is more than enough for a DD making up to 475whp with OEM rev limits, yet tight enough to not wear out the bearings after 100k+ miles.
Also, this engine will make more power than the same block with forged pistons (and no headwork) that are designed for the 2L combustion chamber (big time band-aid)

So if money is a problem, do the new 09 STi SB and get the heads re-chambered. I promise you will be very happy. Just be sure you get a solid tune on it. If you have a FMIC, move the IAT as well.

[pokybear]

Just wanted to say thanks again. All of this information is invaluable, and has really caused me to pause. I'm going to reconsider rebuilding the EJ20, and will research the ECU issues associated with a STI swap. We may still build the hybrid, but I see now that it isn't as clear cut as I had originally thought. Thank you for spending your time responding.

[Halls]

Originally Posted by pokybear

Just wanted to say thanks again. All of this information is invaluable, and has really caused me to pause. I'm going to reconsider rebuilding the EJ20, and will research the ECU issues associated with a STI swap. We may still build the hybrid, but I see now that it isn't as clear cut as I had originally thought. Thank you for spending your time responding.

Just keep in mind that an Sti swap is about as much as ud pay for a hybrid swap or to rebuild ur motor with stout forged internals and some decent headwork. Though if you go with a STi swap ensure you get a complete engine harness with STi ECU,so all you got to do is just swap parts right out.

I have more of a 'piece of mind' going with a hybrid as it's got 0 miles on the block

[TRDRacer]

Seasoned blocks are always better because most of the stress is taken out from the metals and are stouter then new block when rebuilt! Also If you do rebuild with new parts and are using a seasoned block then you will have a motor that might cost a little more maybe $500 if just going with basics Pistons ,Bearings and Rods and will be much stronger with built right with proper clearances! But I do understand about piece of mind! Not having to worry about someone fubaring up a build or clearance somewhere in the build and having a motor not be good, and also price as this hobby is not cheap and comes with big costs to get power or reliability with the power you want!

[Daniel's05WRX]

Originally Posted by pokybear

Thanks to everyone who has shared their thoughts. All great information. Given I don't have an unlimited budget, which of these modifications would you put at the top of the list, or conversely, which would you put at the bottom? Our goal is to build a reliable daily driver that makes 300 to 350 WHP. Thanks again, I'm learning loads!

Everything should b bought but the turbo... Spare no exspense with your bottom end and machine work, will pay off big later

[crashtke]

Originally Posted by Maxwell Power

thanks for the kind words sube-trex.

My opinion based on what I have seen with all the motors we build and from what I have observed on other motors:

Hybrid:
If you're going to do the hybrid, the chamber work is so crucial regardless of power output. I would honestly say, do the headwork OVER a forged piston if your power goal is only 300-350whp.

Here's why: The OEM pistons are known for their cracking when pushed hard or when poorly tuned. However, with a proper tune the engine is very reliable ( Especially if the IAT sensor is moved post intercooler) and very quiet. In a knock free environment the OEM piston and it's tighter piston to wall clearances will give you all the power you desire and the reliability of a stock engine. You will have no piston slap and therefor no worries associated with it. You will be able to drive the car sooner after starting and not have to worry about excessive piston scuffing during warm up. You will have low levels of blowby with the tighter ring gaps and tighter clearances. This creates a cleaner intake tract, cleaner cylinders that are less prone to knock because of less oil vapor carried into the engine. Your oil will last longer too. The new 09 STi shortblocks have a new bearing material that is stronger than previous years as well as ideal rod bearing clearances (a big plus from older STi blocks). The oem rod bearings now come from the factory at .0018". This is more than enough for a DD making up to 475whp with OEM rev limits, yet tight enough to not wear out the bearings after 100k+ miles.
Also, this engine will make more power than the same block with forged pistons (and no headwork) that are designed for the 2L combustion chamber (big time band-aid)

So if money is a problem, do the new 09 STi SB and get the heads re-chambered. I promise you will be very happy. Just be sure you get a solid tune on it. If you have a FMIC, move the IAT as well.

We put down 400 on a wrx hybrid, stock short block, stock heads, stock cams, no port work with only 20 psi on a Killshot rotated S256 Borg Warner. It worked pretty well. No det issues, but then we had very little timing since we were working with higher compression and 93 pump gas. Wonder what we could have made with some chamber work and some cams.

[ledzeppelin240]

Should I be running a td04 as hard as I want then (as long as someone will tune it) with my hybrid? Dam, the 2.2 would be awesome but I'm too far into this now.

[Maxwell Power]

Originally Posted by crashtke

We put down 400 on a wrx hybrid, stock short block, stock heads, stock cams, no port work with only 20 psi on a Killshot rotated S256 Borg Warner. It worked pretty well. No det issues, but then we had very little timing since we were working with higher compression and 93 pump gas. Wonder what we could have made with some chamber work and some cams.

Big big gains to be had with the EQ Tuning CNC Chamber work. The flow gains alone make it worth it. Then add Cams and your making serious power. Kelford 199-E is a great choice with a rotated turbo.