Hey guys, what is your opinion about 10.5:1 Compression pistons and a goal of 400-420WHP on RON98 pumpgas (93 in USA)? I can't seem to find any (recent) information on the internet about this.
Car is going to be my daily driver and has to be somewhat reliable.
I know that the compression ratio is pretty high, but i got those pistons for free. Unfortunately there is no E85 available over here.

Specs:
- B16A2 engine
- L.A. Wetsleeves (81.5mm)
- Eagle rods
- CP 10.5:1 pistons (81.5mm)
- Cometic 0.04" (1.016mm) headgasket
- GSR (B18C4) camshafts
- Compcams springs & Retainers
- Spa turbo log manifold (TMH04)
- Maxpeedingrods GT3076 (.82 rear housing)
- 3" exhaust from turbo to muffler
- ARP headstuds
- ACL Main & Rod bearings
- ACT Xtreme pressure plate + 6 puck sprung disk

Fuel:
- Walbro 255lph pump
- Grams 750cc injectors
- Adjustabje fuel pressure regulator
- AEM Water/Meth injection kit

 

more like 300hp

that cheap Ebay turbo isn't going to work miracles

 

Im not familiar with the manifold but typically the log manifolds are frowned upon for higher HP.

 

there are countless manifolds out there that are better. Don't expect much from a cast iron manifold.

 

Thanks for your response!
The turbo shouldn't be a problem, I ran my stock b18c4 with this exact turbo and manifold. Made 270whp at 10PSI boost and really conservative ignition timing (15*)

 

The SPA cast manifolds are known for a good flow and wastegate placement. At least one of the best cast manifolds available.

 

You could, with that manifold. It doesn't mean you should. I don't think what you're asking for is realistic with that turbocharger and the boost pressures needed to get that power on 93 Octane.
Everything else looks ok to roll except for the manifold and turbocharger combination

 

They're good cast iron manifolds. I think the European crowd uses them pretty often.

Agreed with Shodan however that you're making this much harder on yourself with your choice of turbo & manifold. With that current combination I don't think you'll be able to reach your goals.

10.5:1 CR I'd say is actually a more or less ideal compression ratio for a turbo street 93 octane build.

 

Okay guys, thanks for your responses.
Guess i will see what it will do soon on the dyno.
Manifold and turbo upgrade is next on my list. What would you guys recommend for a turbo not too expensive?
I was thinking about maybe a VS racing turbo.

 

stop looking at cheap, low-grade stuff. You can get a decent, BNIB Turbonetics for around $525. You GET WHAT YOU PAY FOR....

 

Have you opened that turbo up to check the wheel sizes and verify that they match a real GT3076r? That's something I've noticed that plagues a lot of these eBay turbos... I've never seen someone buy a 57 or 50 trim T3/t04e and actually get one, it's always a 46 trim. Some of the really cheap ($100) GT series fakes seem to have similar issues.

Anyway I run an eBay GT3076r .63a/r on a pretty similar setup, some junk "a/c" cast manifold on a b16 with 11:1 comp and forged rods, water meth (375ml nozzle starting at 4psi, progressive ramp until 20psi), 20psi @ 12 degrees total.
According to virtual dyno it makes just shy of 400hp. I can't really attest to the accuracy of that program, maybe others can chime in?

So yeah I'd check out that turbo to see if it's a faithful reproduction. It's definitely not ball bearing but I don't think that should affect power output much... as long as the geometry is right I don't see why it being a knockoff would limit it to 300hp as someone else said.

 

Why haven't you tested it on a REAL dyno ? What do you have to input into your virtual program for it to provide a HP estimate... and is that at the wheels or the crankshaft ?

 

I don't see the point in testing it, seems like an expensive way to validate something that doesn't really matter to me. VirtualDyno calculates HP based on acceleration logs, it's at the wheels. It's a mid 11 second car, if that helps give you an estimate of power output.

 

There are a TON of variables that affect how wheel HP is calculated by a program like VirtualDyno. My EG hatch was a mid 11 second car with only 297 wheel HP (11.55 @ 118mph)... not that this is comparable to your results, because there are still a plethora of variables between your car and mine that makes the direct comparison incredibly unfair.

I understand that a "Dyno Number" doesn't really matter to you. What should matter is the accuracy of your wideband O2 sensor... comparing your in-car data to a high quality calibrated O2 content device is certainly in your best interest... and the best interest of your engine's long term survival. Just a thought...

 

I hope you're being sarcastic but I highly doubt it. I guess you do know more than 99% of us. Of my 25+ years of wrenching on cars, my mind is blown with such idiotic assumptions and idea. Explain to us all how great your Virtual Dyno is.

 

‘the point of a dyno is not about flexing your high numbers , it s more about being able to put a proper load on the motor and getting accurate readings. I’m on wastegate right now and I’m never going to get things tuned just right until I hit the dyno, it’s just not accurate. Once you hit a certain power level street tuning won’t do it anymore, I’m only at 14 psi right now and there is no possible way to street tune at over 30psi. When I get on the dyno I will add a 15% load restriction on the rollers, this will immatate real road conditions like going up a hill and will allow the computer time to log correctly for tuning.

 

Thanks for that, I use the typical Bosch sensor that most widebands use. For low load I listen to a Bosch knock sensor with a headphone amp, otherwise I read plugs. If I'm being honest, maybe I lied. I'd be disappointed if I was making 300whp. The car is about 3000lb with me in it.

My post wasn't intended to be pedantic but I understand tone doesn't carry well over the internet. This is definitely the Honda-Tech warm welcome I've heard about, haha. I don't know how great it is... how accurate is a dyno though? I don't think VD is better, I ran it because I had a mild curiosity... wasn't trying to make a point.

Fair enough. Usually I just go up hills to simulate that... really depends on where you live as to how effective street tuning is. Otherwise I go to the track.

Anyway not trying to derail this thread, was just trying to help the OP.

 

the main reason for a dyno is safety, there is no way in hell I will do a 150mph pull on the street while trying to pay attention to gauges. My street tune is always pretty solid, but limited by speed that becomes a safety factor

 

Oh definitely, even if I was only risking my own safety it's not worth the legal risk. Given that it's just a "fun" car and I don't really race it, I'm happy for now with just a street tune even though I'm probably leaving some power on the table without a proper dyno tune.

 

I guess I will see what it makes on the dyno and let you guys know!
Just for my peace of mind I ordered an AEM Water/Meth injection kit.
If everything goes well the engine is done next week, and the dyno will be short after.

 

Good luck! If you want some extra protection I'd recommend wiring in your wideband to your ECU so you can set a fuel cut if the water meth system ever decides to fail.

Also on my car, the water meth seems to like to kill MAP and TPS sensors. You could probably mount it after the throttle body with a spacer and be OK. In my case I put a filter inline with the MAP sensor and haven't solved the TPS issue yet.

 

I have an actual real GT3076R for sale if you're interested! It has an upgraded CHRA from a GTX3076R Gen 1 let me know if you're interested.