mikesv8z Posted June 12, 2011 Share Posted June 12, 2011 I'm constantly being asked these two questions whats your horse power ,I reply um I'm not sure it's a 89 iroc motor with stock cam and tpi intake but I put 305 HO heads 58cc chambers raising the comp. to about 10 to 1?any guess on hp?I thought maybe 300 ...too much ?Then they look again at the car and say whats it's weight? Don't have a clue missing alot of info. Whats the curb weight of a stock 75 280 could start from there I guess.My car is missing alot I mean alot Quote Link to comment Share on other sites More sharing options...
rsicard Posted June 12, 2011 Share Posted June 12, 2011 Mike: Horsepower at best is 240 if the displacement is 350 cu in. With many parts missing it will be expensive to buy the parts to rebuild. Quote Link to comment Share on other sites More sharing options...
mikesv8z Posted June 12, 2011 Author Share Posted June 12, 2011 Mike: Horsepower at best is 240 if the displacement is 350 cu in. With many parts missing it will be expensive to buy the parts to rebuild. the motor is complete its the car thats been lightened the motor started out with 72 or 76 cc heads I raised the comp from 8.5 to1 to about 10 to 1 240hp is the advertized hp for a stock 350 for that year but it's with all the acc running all I have is an alt. now Quote Link to comment Share on other sites More sharing options...
Pyro Posted June 12, 2011 Share Posted June 12, 2011 going from 8.5 to 10:1 would be worth 10hp in your case. http://www.wallaceracing.com/hp-cr-chg.php this assumes you can still run the correct ignition timing, as all the gains would be lost if the ignition timing had to be retarded to prevent ping. curb weight is about 2850 lbs for a 280z, adding a v8 adds about 150lbs, you could drop 150lb off the car if you remove most everything. to find hp, run your car at the track. Use 1/4 mile trap speed and car weight to calculate hp. Quote Link to comment Share on other sites More sharing options...
Michael Posted June 12, 2011 Share Posted June 12, 2011 Higher compression ratio is more of an enabler for other power-adding modifications (such as a higher-lift, higher-duration cam, without sacrificing low-end torque), than a direct power booster itself. As the principal engine-savvy members on this forum keep reiterating to the rest of us, the route to horsepower gain is through a concerted combination of parts, and not through individual replacement of one or another component. There is no shame in replacing one set of OEM parts with another, if that's what budget considerations dictate, provided that the new set is properly engineering to work with the old. Having gone through a lengthy and circuitous vehicle modification campaign (in addition to just "the swap"), my suggestion would be to bring towards preliminary drivable condition whatever you have now, and reserve as many impending mods as possible for evolutionary improvement after the vehicle runs. This is better than shooting for a high-quality complete vehicle that awaits full attention to detail before making its maiden voyage. It is better to fix lurking surprises on a running work-in-progress, than to fret over how well your baby will perform once ready for the grand unveiling. Quote Link to comment Share on other sites More sharing options...
rossman Posted June 12, 2011 Share Posted June 12, 2011 Having gone through a lengthy and circuitous vehicle modification campaign (in addition to just "the swap"), my suggestion would be to bring towards preliminary drivable condition whatever you have now, and reserve as many impending mods as possible for evolutionary improvement after the vehicle runs. This is better than shooting for a high-quality complete vehicle that awaits full attention to detail before making its maiden voyage. It is better to fix lurking surprises on a running work-in-progress, than to fret over how well your baby will perform once ready for the grand unveiling. ^^Darn good advice! Quote Link to comment Share on other sites More sharing options...
rsicard Posted June 12, 2011 Share Posted June 12, 2011 Michael has good advice. Just raising compression is just one aspect of trying to obtain better engine performance. Buy and study books by David Vizard and you may be ahead of the game. First concentrate on getting the body structure and systems in proper good order. Get it running and driving before working on the engine for more performance. Later year 350 engines were machined by CNC systems and should be more exact dimensions. Before building a performance 350 get a really good block as the foundation for making REAL power. No core shift and adequate cylinder wall thickness. Displacement for displacement the Gen I, Gen II, Gen III and Gen IV are all very similar in power for the same power enhancements. The Gen I has the most amount of cheap performance parts available. Quote Link to comment Share on other sites More sharing options...
kamikaZeS30 Posted June 12, 2011 Share Posted June 12, 2011 I agree with Michael on this one. I would make sure you have a solid bottom end (short block/rotating assembly), all the other performance stuff can be done easily once the car is running and without having to remove the engine. Also, to me, the advantage of putting the v8 in a light car like the 240/260/280Z is the torque, not necessarily top-end power. It makes for a more fun car, IMO. Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted June 21, 2011 Share Posted June 21, 2011 Hey everyone, long time no see. I agree w/michael. Get ur car running, then worry about everything else. Whenever someone asks or wants to bench race hp #'s (and yes its always tempting), i always return with another question. And that is, if u know your static comp then tell me what your dynamic comlression is(?). This is usually followed by shrugged shoulders and blank stares. It is important to understand, as a previous posters said, the engine is a complete pkg. Putting 305 heads on may have increased airflow velocity, but has it really increased cfm? Probably not that much. You are still running small intake port heads with a low lift and short duration cam. Hp increases w/out fear of detonation or ping, must always be approached as a complete package. Never hurts to make little changes along the way as the budget allows as long as you understand what affecfs you are making. Do you rember if your pistons were flat tops or dished? If dished then by how much? Remember that hp is torque measured in time. You are putting a low torque engine in a light weight car. You have already fudged the numbers in the torque game already. Dont worry about high hp numbers until you have the budget to build an engine that can handle higher hp. While your project sits i would do what a previous poster suggested. Begin reading about performance engine modifying. Learn what affecfs are altered when certain components, (with different component parameters) are added and how they affect the outcome. Read books at the bookstore, read everything u can in the hybridz archives, ask lots of questions, and get your car running. Its always fun to come back here!!!!!! Kevin, Yea, still an Inliner Quote Link to comment Share on other sites More sharing options...
johnc Posted June 21, 2011 Share Posted June 21, 2011 When ever someone brags to me how much horsepower their engine makes, I always ask, "Is it running?" Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted June 22, 2011 Share Posted June 22, 2011 When ever someone brags to me how much horsepower their engine makes, I always ask, "Is it running?" I could care less about rwhp, etc. I have raced cars with 800 plus rwhp and shown them my tail lights. I worry more about making power that I can use and making it dead hook! Love the look on their face when they hear me say I only make 550-600rwhp tops. Mike Quote Link to comment Share on other sites More sharing options...
TTV8 Posted June 22, 2011 Share Posted June 22, 2011 If they post a dyno sheet it must be running. If not it's just a bs guesstimate. Half the top 25 here don't even have timeslips to verify their 1/4 mile times. On My350Z they wouldn't even be on the list without verification. Quote Link to comment Share on other sites More sharing options...
Zfan1 Posted June 23, 2011 Share Posted June 23, 2011 If they post a dyno sheet it must be running. If not it's just a bs guesstimate. Half the top 25 here don't even have timeslips to verify their 1/4 mile times. On My350Z they wouldn't even be on the list without verification. I have a video to verify mine...LOL Quote Link to comment Share on other sites More sharing options...
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