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| Turbo a 198 or 170 instead of a 225? https://slantsix.org/forum/viewtopic.php?t=55420 |
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| Author: | Tim_K [ Fri May 23, 2014 12:33 am ] |
| Post subject: | Turbo a 198 or 170 instead of a 225? |
Hi, I've been away for quite a while, since the end of 2008 according to the site, but I stopped in to read some stuff yesterday, and was surprised and pleased to see what looks like quite a bit of development in turbocharging the Slant 6. From what I read, it seems like the 225 becomes a real torque monster with a bit of boost on it, but has anyone turbo'd a 198 or 170? Seems to me they'd do well with it, and their shorter strokes would allow a better rpm range. I know that Toyota and Nissan can make some huge power numbers with their 2JZ 3.0 liter 6, and Nissan's RB26DETT in the Skyline. Both are small displacement straight sixes of 2.6 and 3.0 liters, right between the 170 and 198. But then again, they have some good ports in their DOHC heads, and we have the stock head to deal with. If I ever decided to do a Turbo Slant project, I think I'd start off with getting MegaSquirt running on a bone stock Slant 6 with fuel injection, then once that was figured out, add the turbo and reprogram the fuel map for the boost. |
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| Author: | Charrlie_S [ Fri May 23, 2014 4:28 am ] |
| Post subject: | |
I have a 65 Valiant with a draw thru turbo on a 170. Originally built about 1979. It uses a Holley 500 cfm 2bbl on the inlet of a modified Corvair (Rajay) turbo. |
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| Author: | Dart270 [ Fri May 23, 2014 5:56 am ] |
| Post subject: | |
I have a well sized turbo and 170 core motor and am starting a build. I will do mulit-pt EFI with Megasquirt III. Lou |
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| Author: | Tim Keith [ Fri May 23, 2014 6:33 pm ] |
| Post subject: | |
The 170 is a little smaller in displacement than a 2JZ. A 170 in a light car would be fun even with 7 lbs boost. The Datsun 280ZX turbo were about the same displacement. I think a turbo slant six could do better with newer technology than those older Nissan turbos. I know little about turbo system design but I think the turbo 225 slant six might feel more like a 273. |
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| Author: | billdedman [ Sat May 24, 2014 9:51 pm ] |
| Post subject: | slant power... |
You think it might feel like a 273? How do you think this one feels? http://www.youtube.com/watch?v=7QzUfV8iTpQ I'd say it probably feels more like a 440... LOL! I have a car like that (mechanically.) I realize that I will be extremely lucky to get it to run within two seconds of this car in the video... extremely lucky!!! I can only hope...  Bill, in Conway, Arkansas |
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| Author: | MJF [ Sat May 24, 2014 11:45 pm ] |
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Local guys had big turbo 225 and when they blew head gasket, they swapped temporary stock 198 to finish racing season. In couple runs it blew gasket too, but what they told was it revved soo much happier than 225 they had. 225 had ported big valve head and light forged pistons, and 198 had quick pocket porting and otherwise stock engine. Cam was swapped from 225. 198 did run 13,9/109mph @8psi. I have their 198 now, we´ll see how it runs... |
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| Author: | Rick Covalt [ Sun May 25, 2014 5:10 am ] |
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I'm not sure I follow the 198 being better. From what I read the guys making big horsepower are not turning big RPM anyway. If a turbo motor is making 1.5 Hp/cu in, then you are giving up 40+ horsepower from the start. And don't they say there is no replacement for displacement?  Just a goober thinking out loud. Good luck! |
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| Author: | slantzilla [ Sun May 25, 2014 5:51 am ] |
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For a street motor why would you want to handicap yourself with less cubes to start with? |
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| Author: | Dart270 [ Sun May 25, 2014 7:59 am ] |
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I have two reasons for the 170: 1) Meet class displacement at Bonneville (< 3.0 L) and I might get an unlimited record by bumping down one weight class down in Slant 6 racing. 2) I am curious how the higher revving 170 will work with a good head and turbo. We'll see... Lou |
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| Author: | slantzilla [ Sun May 25, 2014 10:10 am ] |
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How high will a 170 actually rev? I've had my 225 to 6500 repeatedly on the hose, 7000 on muscle. |
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| Author: | billdedman [ Sun May 25, 2014 11:42 am ] |
| Post subject: | 170 revs... |
Pete McNicoll (one of the original Ramchargers) had a naturally-aspirated 170 in a 40 Willys coupe Gasser at the Indy NHRA nationals in 1961, won his class handily, and the word was, he was spinning it 8,000 rpm, and it sounded like it!!! It ran 14-flat @ 100 mph... way faster than anything else in his class. Bill in Conway, Arkansas |
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| Author: | Dart270 [ Mon May 26, 2014 3:56 am ] |
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As long as the valvetrain can be made to work, 8000 should be no problem. 7000 is really pushing it for a 225, in my book. Remember, I want to hold the revs for many seconds or even minutes. Lou |
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| Author: | Tim_K [ Tue May 27, 2014 8:51 pm ] |
| Post subject: | |
I'm thinking a 198 might be the optimum combination of revability and power. It should be able to go to 6500 rpms with no problems, maybe just a good set of valve springs. My last car was an 89 Spirit ES with the 2.5 Turbo and a 5 speed. The 2.5 has nearly the same stroke as a 225, and even though it was 2/3 of the displacement, it had no problems at all in getting the car up to speed quickly. The 2.2 Turbo is essentially the same as a 198 except only 4 cylinders, and the 2.2's made big power numbers also. The 225's are good, but they demand too much airflow of a cylinder head that is mediocre at best, and the long stroke limits the rpms. |
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| Author: | billdedman [ Tue May 27, 2014 10:49 pm ] |
| Post subject: | 225 vs. 198... |
Good points, all, but since it costs exactly the same, why not build the bigger motor? The extra cubic inches will more than offset any perceived disadvantages compared with a 198, I believe. Just my 2-cents... Bill, in Conway, Arkansas |
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| Author: | slantzilla [ Tue May 27, 2014 11:24 pm ] |
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Quote: As long as the valvetrain can be made to work, 8000 should be no problem. 7000 is really pushing it for a 225, in my book. Remember, I want to hold the revs for many seconds or even minutes.
But that's not for a street car. Lou  A few minutes at 8000 will take pretty good valve springs and pushrods, probably a spray bar too to cool the springs. |
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