ATTN: tech guru's and turbo junkies.

[hek1620]

i think i'm going to be getting a new turbo soon. i've seen many people happy with a t3/t04e 57 trim on the ka's. especially the sohc. no as most of u know my motor is rebuilt to stock. so i'm not trying to go crazy. but i want to buy a turbo that will allow me to make a good amount of power without stressing the motor. this is where i need technical advise. the way i see it, to be less stressfull on the motor u would use a bigger turbo with less psi. right? i would like to be in the high 300's at the wheels. at least. any suggestions would be greatly appreciated. also, if u also let me know how much/which injectors i'm going to need. thanks again.

[hek1620]

i think i'm going to be getting a new turbo soon. i've seen many people happy with a t3/t04e 57 trim on the ka's. especially the sohc. no as most of u know my motor is rebuilt to stock. so i'm not trying to go crazy. but i want to buy a turbo that will allow me to make a good amount of power without stressing the motor. this is where i need technical advise. the way i see it, to be less stressfull on the motor u would use a bigger turbo with less psi. right? i would like to be in the high 300's at the wheels. at least. any suggestions would be greatly appreciated. also, if u also let me know how much/which injectors i'm going to need. thanks again.

[Florida240sx]

555cc or 650... best to go with 650 or 740cc so you don't need to change fuel set-up if you upgrade your engine later.

[C-Kwik]

Don't be so concerned with just bigger. The most important factor is efficiency at the boost pressures and airflow levels your motor will be operating in, especially where it's making the meat of it's power. A 50 trim T04E compressor will likely provide better efficiency than the 57 trim if you're looking towards reaching in the neighborhood of 400 HP. Another important aspect is to size the turbine and turbine A/R to better match the operation efficiency in the power area of the engine's operaion. If you're nearing 400 HP, any T3 turbine will likely become a restriction. T3 turbines are great for response, but if a lot of your focus is on keeping the engine happy, reducing heat and backpressure is a much safer way to get a little bit of extra power over increasing the boost levels.

I will say though, that reaching your desired power levels may be a stretch on a stock bottom end.

[nissanfanatic]

I agree with C-Kwik. That is why I stopped at 420whp on my setup. The turbine is a restriction at any AR size due to the size of the T3 flange itself.

Just make sure you have everything right in your setup if you are going to do this on stock bottom end.

[rotorimp]

On a stock motor if you want to keep it any lenght of time I would lower your goal by at least a 100hp!

[480sx]

A bigger turbo is going flow alot more air than a small one. Even with slightly less boost, more air will get forced into your engine. Its much easier to blow a motor with a big turbo than a small one, it lessens your margin of error with your tune.

Also your HP goals arnt really realistic at all. 300 hp is not a small amount of hp, on a stock motor you are definitely 'stressing' your bottom end even at that level. Fanatic has run 21 pounds of boost and reached over 400 hp with the stock bottom end, but many people have had massive engine failure at much less. In fact, its much more common to throw rods through the block at around 350 hp, or blow ring lands.

If you want an engine thats going to last, you need to spend money on a professional dyno tune. Honestly, the main reason most peoples engine blows is due to poor tuning. However with a stock bottom end, anything over 300 is getting into the 'good luck' phase of tuning. Beyond tuning, the stock rods and pistons simply arnt built to withstand much more than 300 hp. One tiny mistake in your tuning and your engine is toast.

Anyway, all of the information you seek has already been covered, come to the ka-t forum and spend some time reading into our sticky posts. You can learn alot from them, after that, just ask us.

EDIT- When this post was tossed into this forum, it was in the 240 tech section, i was the first person to reply. Sorry for any seemingly redundant or out of place information.
Modified by 480sx at 10:26 PM 4/24/2007

[hek1620]

i've been on ka-t for awhile. i posted this overthere, i think. anyways, i know it's a bit of a gamble. and maybe that's a bit much. but my engine is rebuilt, and i tune the ecu. using help from the guys at hybridka. there's tons of people doing the same. so back on topic. what turbo do u guys think would be efficient for these power levels on a ka?

[hek1620]

sorry, posted something here for another page. disregard.
Modified by hek1620 at 9:28 AM 4/23/2007

[WDRacing]

A bigger turbo is going flow alot more air than a small one. Even with slightly less boost, more air will get forced into your engine. Its much easier to blow a motor with a big turbo than a small one, it lessens your margin of error with your tune.

Also your HP goals arnt really realistic at all. 300 hp is not a small amount of hp, on a stock motor you are definitely 'stressing' your bottom end even at that level. Fanatic has run 21 pounds of boost and reached over 400 hp with the stock bottom end, but many people have had massive engine failure at much less. In fact, its much more common to throw rods through the block at around 350 hp, or blow ring lands.

.

Wrong all around. The bigger turbo will be far better then a smaller one, T28, T3 super60 because it doesn't heat the charge air as much causing detonation. The only thing that would happen is a boost spike, wastegate issue or boocst controller issue. All of which if done right will not be a problem.

Also, 300WHP can be done ALL day on a KA if put together correctly.

[S13FX]

t3/to4e will do jsut fine get something like a precision GT32. Thier great turbos, and don't cost an arm and a leg.

Off Topic. I would like to see a vid of the hole the rod put through the block I bet you could even drive around like that for a bit too :-p

[hek1620]

The bigger turbo will be far better then a smaller one, T28, T3 super60 because it doesn't heat the charge air as much causing detonation.

that's was my impression.

[C-Kwik]

A bigger turbo is going flow alot more air than a small one. Even with slightly less boost, more air will get forced into your engine. Its much easier to blow a motor with a big turbo than a small one, it lessens your margin of error with your tune.

As I discussed already, size isn't as important as knowing a turbo's efficiency at given airflow rates. Bigger turbos as a general rule do tend to be more efficient at higher airflow rates, but it's not always the case.

However, running a more effcient turbo for the boost and airflow you're running will provide a cooler charge. This has a few benefits. The obvious one is that cooler air lessens the chances of detonation occuring as Brian already mentioned. Another is a denser charge which equates to more potential power in each combustion cycle. If a specific HP level is the goal here, then it can be tuned to achieve that goal and run more conservatively on boost by perhaps running a bit higher compression ratios, maybe a bit leaner, and perhaps more timing advance. An added benefit of a cooler charge is that the intercooler is not as burdened. It can free up options to run a smaller I/C, or keep coolong capacity the same and provide more consistent charge air cooling and perhaps keeps a higher ceiling before heatsoak can occur. The latter 2 are quite beneficial if the car is tracked as the conditions are much more harsh for the intercooler on a track than on the street.

Another benefit I touched on already is the turbine side. A more efficient compressor for the given airflow and boost levels will reduce backpressure with any turbine. Match the turbine's peak efficiency areas with the compressors as well and there will be much less backpressure. Reducing backpressure will free up more HP, again, allowing you to run less boost to achieve a given HP rating. It will reduce the load on the bottom end as well. Lastly, lower backpressure means less heat, particularly at the exhaust valves. Hot exhaust valves can become a starting point for detonation. If you can reduce the chances of detonation, you can increase compression, run leaner, and/or advance timing and actually get even more power.

This all being said and going back to the issue of generalizing that bigger turbos flow more air, consider that a large turbo operating at a low boost level that puts it out of a reasonably desirable efficiency level will not perform or flow as well as a small turbo operating within it's peak efficiency areas. Turbo sizing should not put as much attention to larger or smaller as it should towards it's efficiency at the desired boost and airflow levels.

[480sx]

WD my post had nothing to counter what you said, i was just playing devils advocate with the comment about a bigger turbo with less psi being safe. I never said running a smaller turbo was a good idea. The only way to be safe with a turbo is by having a good tune, and knowing your setups limits.

You are however right about a smaller turbo generating more heat when trying to reach higher boost levels, where a t3/t4oe is much more efficient.

Also, for the ONE guy we have pushing 400 hp, how many threads have you seen about blown KA-T's? Of course if every things right you can run 300 all day, the sames probably true about 350. However, most people dont get it right their first time. Its always a setups weakest link, and its been found, quite a few times. One if this guys main concerns was reliability, and a reliable, daily driven 400 hp car is a rare breed. We obviously all love the Ka, but you have to admit, they are blown up alot. FOR WHATEVER REASON, that statement is true.

Edit - S13FX, youv never heard of a rod going through the block? While i cant vouch for a rod literally going all the way through, a rod will definitely leave a huge gouge in the block in some cases. Grenading an engine isnt a term without base in reality lol. While iv never seen it, i have heard stories. I have however seen valves melted into pistons, thats pretty cool too ^^.
Modified by 480sx at 10:24 PM 4/24/2007

[hek1620]

search around. i've seen the pics here of huge jagged holes on the side of a ka where the rod punched through.

[WDRacing]

Edit - S13FX, youv never heard of a rod going through the block? While i cant vouch for a rod literally going all the way through, a rod will definitely leave a huge gouge in the block in some cases. Grenading an engine isnt a term without base in reality lol. While iv never seen it, i have heard stories. I have however seen valves melted into pistons, thats pretty cool too ^^.

Modified by 480sx at 10:24 PM 4/24/2007

Both Fiznat and I had the #3 rod punch a hole in the block.

[S13FX]

Edit - S13FX, youv never heard of a rod going through the block? While i cant vouch for a rod literally going all the way through, a rod will definitely leave a huge gouge in the block in some cases. Grenading an engine isnt a term without base in reality lol. While iv never seen it, i have heard stories. I have however seen valves melted into pistons, thats pretty cool too ^^.

Modified by 480sx at 10:24 PM 4/24/2007

I think you missed the point of my joke lol. I have literately seen pistons before fly through head of the block and come out the hood, funniest **** ever and it sounds just like a gun shot .

[nissanfanatic]

I still can't see the destruction of a vehicle humorous unless that was it's intent..

Cars blowing up when success is the intention is depressing IMO...