Hey guys, I’m new to the message board thing but I have been reading little while now and have never posted I have used the search but to no avail the info that I would like is not present (at least not that I could find)
My dilemma is this I need to rebuild my 2gnt (Spun rod bearing) and would like to know what my best options are. Do I rebuild at 8.5:1, 9.5:1, or higher I will be adding a forced induction as soon as my budget allows but that will still be quite a while. Correct me if I am wrong but the stock 2gnt on produces about 140 hp and is running 9.5:1 if I rebuild to 8.5:1 my hp goes down by 4% witch will leave me running even slower than I am now witch I don’t think I could take but it seem that it would be the most popular way to go.
My questions are these
If I rebuild the bottom end with Weisco pistons and eagle rods. The head with a stage 2 port and polish running stock cams upgraded fuel pump and larger injectors what would I be looking at in the range of Hp for the following.
(if I have not included enough info please use your best judgment on what is missing and let me know what other info is required to make a educated guess on the following questions.)

At 8.5:1 CR NA =? Hp
Boost at 7psi =? Hp
Boost at 15psi =? Hp
Boost at 20psi =? Hp

At 9.5:1 CR NA =? Hp
Boost at 7psi =? Hp
Boost at 15psi =? Hp
Boost at 20psi =? Hp

What would be the issue of boosting a 10.5:1 CR engine?
I have not seen anyone running above 9.5:1 compression and having there engine turbo charged but I’m not sure exactly why I think that the octane you would need is just insane (especially for a daily driver) and or the amount of pressure in the combustion chamber would just be too much for the parts to handle. If I am wrong or only partly correct please let me know.

Can boosting a high compression engine be done safely?

What formula is used to determine the maximum safe boost at each compression level and the amount of ponies that will be produced?
any info would be helpful
Thanks Guys

you can't predict hp like this very accurately, but mathamatically:

variables/assumptions (too many, too fuzzy):
4% for 1 chante in cr
115 hp @ wheels bone stock
210 hp @ wheels hrc stage2 kit 7psi
13.5 hp / psi (which is carried thru psi range calculations)


approximations:
lower compression ratio
At 8.5:1 CR NA = 110.4 Hp
Boost at 7psi = 201.6 Hp
Boost at 15psi = 304.8 Hp
Boost at 20psi = 369.6 Hp

stock compression ratio
At 9.5:1 CR NA = 115 Hp
Boost at 7psi = 210 Hp
Boost at 15psi = 317.5 Hp
Boost at 20psi = 385 Hp


note: these numbers may not be anywhere near reality. all the calculations are based on the fact that you COULD get 210 hp at the wheels w/ a hrc2 kit, which would technically give you 13.5hp per psi of boost, and IF that carried thru the whole psi range, that's what you'd be looking at w/ the respecitve compression ratios. this isn't the case thou. i doubt very much that you'd get over 300 to the wheels w/ a hrc3(st2+internals) kit. i think someone just dyno'd at 266 @ the wheels at 15psi if i remember correctly. 8.5 compression was it? but i think that was a star kit, which SHOULD output more hp b/c of the bigger t3t4. like i said, there are too many variables to predict hp. those real numbers would make these "calculated" numbers about 40hp off @15psi not including the fact he's got a completely different setup than the variables/ass's of this "calculation". at 20psi it would be an even worse error. catch my drift?

>>>What would be the issue of boosting a 10.5:1 CR engine?
you need your fueling to be perfect.

>>>I have not seen anyone running above 9.5:1 compression and ...
i'm not sure, i don't know if the engine could handle it even if you did have adequate fuel tuning. anyone know?

>>>Can boosting a high compression engine be done safely?
maybe.

>>>What formula is used to determine the maximum safe boost at ...
not sure there is one, just like the formulas above don't work because if that 13.5 ratio is off by even a hair, it gets progressivly worse the higher psi you multiply it by, and the more skewed the resulting hp numbers are. that and even if that number IS exactly rite, i don't think it carries thru the whole psi range, thus making this whole conversation null and void. do it and dyno it and that'll be the only REAL way to answer u're question of hp numbers

last edit: these also don't take into account ANYTHING else about u're engine. like the p&p stuff you said earlier or anything else for that matter...

-bryan
'98 rst

thank you for your time and the info.

no problem, anytime. but i'm also curious about higher compression and turbo. is there anything else besides REALLY watching u're fuel situation and u're other gauges that you would need to do to an engine in order to run 9.5 or 10.5 safely on a boosted car?

-bryan
'98 rst