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power gains?
https://slantsix.org/forum/viewtopic.php?t=39189		 Page 1 of 1
Author:  hello, operator [ Sat Feb 27, 2010 5:53 pm ]
Post subject:  power gains?
i have a few simple questions that i couldn't find on search. i understand that the 1964 225 slant was rated at 8.4 compression, but was closer to 7.4. Its horsepower rating was 145, 210 torque. Are the hp and torque numbers accurate for a stock motor? generally speaking, how much more power would one expect from milling the deck of the block to get 9.0 compression?
thanks.
Author:  Aggressive Ted [ Sat Feb 27, 2010 6:16 pm ]
Post subject: 
They are accurate if the motor is in good tune with a fresh rebuild. Bumping up the compression will provide another 20 HP. It is hard to stop with compression increase alone, but it really helps allot. Start ups are much quicker and the torque and mileage comes up too. Your car will be allot more fun to drive!
Author:  SlantSixDan [ Sat Feb 27, 2010 6:37 pm ]
Post subject: 
No, the numbers aren't really reflective of reality. See this post for discussion of horsepower numbers.

GM tested a Chrysler aluminum 225 in 1961. They got 127 horsepower out of it. I would need to re-read the report to see what its configuration was in terms of engine-driven accessories, air cleaner, exhaust system, etc.
Author:  hello, operator [ Sat Feb 27, 2010 6:50 pm ]
Post subject: 
hmmm... that is most unfortunate. good to know that decking the block gives some good gains. I am hopeing to give a friend of mine a run for his money when i get my roadster built. his 1.8 L turbo golf gti vs my slanter. he is 800 pounds heavier than me, but he also has around 200hp :cry: perhaps decking the block, along with some crafty headers and an intake will put him in my dust (at least in the 1/8th.) thanks for the help guys, im just a motorhead with a little to much time on my hands i guess.
Author:  Joshie225 [ Sat Feb 27, 2010 6:56 pm ]
Post subject: 
A ported head with big valves helps a lot. Get the compression ratio up, choose a good cam, small 4bbl, the ported head and headers will get you close to 200hp. Gotta tune it right though!
Author:  SlantSixDan [ Sat Feb 27, 2010 7:11 pm ]
Post subject: 
Don't just start shaving the block or head. Don't just start buying parts. You need to do a lot more talking and listening, and ask a lot more specific questions about your car and your goals, before a clear picture will emerge of what to do and buy and spend.
Author:  hello, operator [ Sat Feb 27, 2010 7:12 pm ]
Post subject: 
unfortunately, the internals of the motor cant be changed right now because of budget constraints (a.k.a no budget at all ha ha) but bigger valves and some material off the block is certainly something to keep in mind for the future. im looking foreward to showing off my build to you guys soon. thanks again.
Author:  hello, operator [ Sat Feb 27, 2010 7:23 pm ]
Post subject: 
i have actually been doing tons of lurking and researching on this site. in fact, this site is the reason why i got a slant. ( i was looking for the most dependable motor possible.) like i said in my last post, i wont be fiddling with the motor for awhile, but when i start on building the headers and intake, ill post lots of pictures and look for lots of feedback.
Author:  Charrlie_S [ Sun Feb 28, 2010 6:06 am ]
Post subject: 
If budget is a big issue, then milling the head is the best bang for the buck (providing everything else is in good condition). Every slant I have taken apart and measured, was less then 8-1 compression. I pulled a good condition head off my 66 Valiant and had it milled .100 for $60 (your price may vary), put it on with no other changes, and went .3 sec, and 3 mph better in the 1/4 mile.
Author:  hello, operator [ Sun Feb 28, 2010 8:01 am ]
Post subject: 
taking off .100 would still allow 87 octane right? can a gasket set be obtained from the local parts store without a problem? is there a problem with taking that much material off the head? thanks.
Author:  dakight [ Sun Feb 28, 2010 10:03 am ]
Post subject: 
Don't just start cutting the head. Mesure the deck clearance and combustion chamber volume first then you wil be able to calculate the compression ratio and adjust the chamber volume to get what you want rather than just guessing. The factory parts are all over the map so for best result you really need to measure.... and that doesn't cost anything.
Author:  Charrlie_S [ Sun Feb 28, 2010 5:29 pm ]
Post subject: 
What dakight said. Think like a carpenter, measure twice and cut once. I just used my engine as an example.
Author:  66aCUDA [ Sun Feb 28, 2010 5:30 pm ]
Post subject: 
To answer your questions. MEASURE, however, gaskets are readily available at most parts stores. When you put on a "new" Felpro gasket you loose .028 just from using that gasket rather than a steel shim "factory" gasket. So .100 becomes .072 effective change in deck height. There were 2 different motors in the slant family in 64 a 170 and 225. You will need to know which you have as they are very different inside. Tell us how long the small hose from the head to the block is on the front of the motor. About 1 inch is a 170, 3 inches is a 225.???
Frank
Author:  hello, operator [ Sun Feb 28, 2010 8:52 pm ]
Post subject: 
thanks for the info on the head gasket (that saved me a headache for sure) ill be sure to measure 10 ways from Sunday, and the hose in front is three inches long.
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